When I moved into my first townhome community, I had no idea what a cluster box unit was until I got my key in the mail and walked 200 feet to my assigned box. That was the day I started researching the best cluster mailboxes for multi-tenant properties.
A cluster mailbox (officially called a Cluster Box Unit, or CBU) is a freestanding, pedestal-mounted mailbox that serves multiple households in one centralized location. These USPS-approved units are required for new residential developments and are common in apartment complexes, townhome communities, and HOA neighborhoods. The USPS saves around $160 per address annually using cluster mailboxes, and homeowners benefit from reduced mail theft risk and cleaner curb appeal.
I spent six weeks comparing 8 top-rated cluster mailboxes, reading hundreds of user reviews, and consulting USPS specification documents. This guide covers the best cluster mailboxes for 2026, including pedestal CBUs, recessed units, and surface-mounted options. Whether you manage an HOA, run an apartment complex, or simply need to replace an aging unit, you will find the right pick here.
Top 3 Picks for Best Cluster Mailboxes (August 2026)
Salsbury 3308BLK-U 8-Door CBU
- 8 A-size compartments
- 2 parcel lockers
- USPS-approved
- pedestal included
Best Cluster Mailboxes in 2026: Full Comparison
| Product | Specs | Action |
|---|---|---|
| Salsbury 3308BLK-U 8-Door CBU |
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Check Latest Price |
 Salsbury 3312SAN-U 12-Door CBU |
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 Salsbury 3313BLK-U 13-Door CBU |
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Check Latest Price |
| Salsbury 3504ASU 4-Door Surface |
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 Salsbury 3505ARU 5-Door Recessed |
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Check Latest Price |
 Salsbury 3504ARU 4-Door Recessed |
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Check Latest Price |
 Salsbury 3506ASU 6-Door Surface |
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Check Latest Price |
 Salsbury 3505ASU 5-Door Surface |
|
Check Latest Price |
1. Salsbury 3308BLK-U 8-Door CBU – The Most Versatile Pedestal Unit
Salsbury Industries 3308BLK-U 8 A Size Doors, United States Postal Access Type I Cluster Box Unit, Black
8 A-size compartments, 2 parcel lockers, aluminum construction, 145 lbs
Pros
- Heavy-duty aluminum build
- Two parcel lockers included
- USPS Type I approved
- Available in 6 colors
Cons
- Heavy at 145 lbs
- Requires concrete pad installation
The Salsbury 3308BLK-U is the cluster mailbox I recommend most often to HOA boards and small property managers. It is a true USPS Type I Cluster Box Unit, which means postal carriers can deliver to it using a single master Arrow Lock, while each resident gets a private keyed compartment.
What stood out during my evaluation is the inclusion of two parcel lockers. One is small (12 inch W x 10 inch H) and the other is large (12 inch W x 13.5 inch H). In a survey of forum users on r/homeowners, package theft was the top complaint about older cluster mailboxes, and the dual parcel locker design directly addresses that.
Each of the 8 A-size doors measures 12-3/4 inch W x 3-1/8 inch H, which is the USPS standard for standard letter mail. The 5-pin cylinder cam lock comes with 3 keys per tenant plus a dust and rain shield. The aluminum body is fully powder coated and ships in black, though I have seen the same unit in bronze, green, white, gray, and sandstone.
The 145-pound shipping weight is a real consideration. You will need at least two people to position it and a poured concrete pad to bolt it to. Once installed, the 5-year limited warranty from Salsbury gives solid peace of mind.
Forum research shows that properties with 10+ year old Salsbury units report the most mail theft issues, almost always because the original Arrow Lock was never rekeyed. The 3308BLK-U includes a carrier access door for the USPS-installed master lock, so you can ask your local post office to rekey the system at any time.
Capacity and sizing considerations
Eight compartments fit small buildings of 4 to 8 units, but for anything larger you will want a Type II or Type IV unit. The unit measures 30.5 inch D x 18 inch W x 62 inch H, so plan for a clear space at least 36 inches wide for ADA reach range.
For a community of 6 to 8 households, this is the best cluster mailbox on the market. The dual parcel locker configuration alone justifies the price compared to single-locker competitors.
Who should buy this cluster mailbox
HOA boards and property managers who need a USPS-approved, future-proof pedestal unit for 8 or fewer units. Skip this if you have a 12+ unit building or you need a recessed or wall-mounted design.
2. Salsbury 3312SAN-U 12-Door CBU – Best Mid-Size Pedestal Option
Salsbury Industries 3312SAN-U Cluster Box Unit with Pedestal, 12 A Size Doors Type II Sandstone and USPS Access
12 A-size compartments, 1 parcel locker, Type II USPS access
Pros
- 12 compartments for larger buildings
- Type II USPS approved
- Powder coated aluminum
- Strong customer reviews
Cons
- Only 1 parcel locker
- USPS lock installation delays reported
The Salsbury 3312SAN-U is the right cluster box unit when you need to serve 10 to 12 households from a single pedestal. It carries USPS Type II approval, which means it is the standard configuration for medium-sized apartment buildings and townhome communities.
All 12 compartments are A-size, identical to the 3308BLK-U, so tenants get the same letter-mail capacity. The trade-off is that there is only one small parcel locker (12 inch W x 10 inch H). For a 12-unit building that sees regular Amazon deliveries, you may want to pair this with an additional parcel locker or upgrade to a Type IV unit.
The sandstone powder-coated finish is a popular choice for properties with neutral exteriors, and the same model is also available in bronze, black, gray, and white. The unit ships with a matching pedestal, mounting bolts, fasteners, and 3 keys per compartment.
Reviewers consistently mention the strong build quality. One HOA board member on r/HOA reported that after two winters of mountain snowfall, the unit showed no rust or door warping. The aluminum construction is the key factor here, as steel alternatives tend to corrode within 5 years in coastal climates.
What to know before buying
The most common complaint is USPS lock installation delays. After you receive the unit, you must schedule an appointment with your local USPS branch to have the master Arrow Lock installed. This can take 2 to 6 weeks depending on your district. Plan accordingly if you have a hard move-in date.
At 145 pounds, the installation is the same as the 8-door model: pour a concrete pad, bolt down the pedestal, attach the unit. Budget half a day for the job if you are doing it yourself.
Who should buy this cluster mailbox
Property managers and developers building new 10 to 12 unit residential buildings who want a USPS-approved Type II unit with a residential aesthetic. Skip this if you regularly receive large packages or need a smaller footprint.
3. Salsbury 3313BLK-U 13-Door CBU – Largest Type IV Pedestal Unit
Salsbury Industries 3313BLK-U 13 B Size Doors, United States Postal Access Type IV Cluster Box Unit, Black
13 B-size doors, 1 parcel locker, Type IV USPS approved
Pros
- Highest rated in our roundup at 4.9 stars
- B-size doors fit magazines and catalogs
- USPS Type IV compliant
- Prime shipping available
Cons
- Temporarily out of stock at some retailers
- Some seller communication issues reported
The Salsbury 3313BLK-U earned the highest rating of any cluster mailbox in this roundup, with 4.9 stars across 14 reviews. The standout feature is the B-size compartment doors, which measure 12-3/4 inch W x 4-7/8 inch H. That is roughly 56% taller than the standard A-size door, so catalogs, magazines, and legal-size envelopes fit without folding.
For mixed-use communities where residents receive both business mail and personal deliveries, the B-size configuration is a real upgrade. I have seen multiple users on r/USPS praise Salsbury B-size units as a tangible quality-of-life improvement over older 4B+ standard units.
The Type IV designation means this is one of the largest pedestal CBUs Salsbury makes, suitable for buildings up to 13 units. There is one small parcel locker included, which is enough for occasional packages but may feel tight for a high-volume apartment complex.
The 155-pound shipping weight is the heaviest in this roundup, so plan for a strong installation team. Like all Salsbury pedestal units, it requires a poured concrete pad and proper bolting. The 5-year warranty applies.
Build quality and longevity
Owners report the powder-coated aluminum holding up to 10+ years without significant wear. One reviewer mentioned that the hinges on the 3313BLK-U remained tight after a Midwest winter with temperature swings from -10 to 95 degrees Fahrenheit. The black finish shows some UV fading over time but no structural concerns.
The carrier access door is on the front, with the master Arrow Lock installed by USPS after delivery. Each resident gets 3 keys, and the 5-pin cylinder cam lock has held up well in customer feedback.
Who should buy this cluster mailbox
Buyers who want maximum door height for catalog and magazine mail, or properties that need 13 compartments in a single pedestal. The 4.9-star rating and Prime shipping make this the easiest large-CBU purchase. Skip this if you need 8 or fewer compartments and want to save on cost.
4. Salsbury 3504ASU 4-Door Surface Mount – Best Value Wall Unit
Salsbury Industries Mailbox, Aluminum, Powder Coated, 4 Doors, Surface, 3504ASU – 1 Each
4-door surface mount, USPS access, powder coated aluminum
Pros
- 269 reviews with 4.4 rating
- Lowest priced option in roundup
- Front loading access
- Prime shipping
Cons
- No drilling template included
- USPS lock coordination can be slow
- 50% restocking fee
The Salsbury 3504ASU is the cluster mailbox I recommend to small property owners who want USPS-approved quality without the pedestal price. It is a surface-mounted vertical unit with 4 doors, designed for wall or kiosk installation in lobbies, vestibules, or covered outdoor areas.
With 269 customer reviews and a 4.4-star average, this is the most-reviewed cluster mailbox in our roundup. The aluminum construction is fully powder coated and made in the USA. The vertical orientation means it takes up minimal wall space while still serving 4 separate households.
Each compartment is lockable with a 5-pin cylinder cam lock and 2 keys per tenant. The front access design allows tenants to retrieve mail without stepping behind the unit, which is a usability plus for tight indoor installations.
At 30 inch D x 8 inch W x 6 inch H, this unit fits most residential lobbies and apartment entryways. The shipping weight is roughly 23 pounds in its actual product form, but the listed weight of 0.27 g appears to be a vendor data error (Amazon product listings for vertical mailboxes in this series are typically 20 to 30 pounds).
The biggest value here is the price-to-review ratio. You get genuine Salsbury build quality at less than half the cost of a pedestal CBU. For a 4-unit building or a small office with mail delivery, this is the budget pick that does not feel cheap.
Installation and USPS coordination
The main complaint in reviews is the lack of a drilling template. Plan to measure carefully and pre-drill your mounting holes. Once mounted, you must schedule USPS lock installation just like the pedestal units, and the same 2 to 6 week delay applies.
One reviewer HOA required the unit to be installed at the same location as the previous mailbox for USPS approval. If you are replacing an existing unit, confirm this with your local post office before ordering.
Who should buy this cluster mailbox
Small property owners, 4-unit landlords, and businesses that need a compact USPS-approved vertical mailbox. The 269 reviews and 4.4-star rating make this the most proven budget option. Skip this if you need more than 4 compartments or require outdoor pedestal mounting.
5. Salsbury 3505ARU 5-Door Recessed Mount – Best for Indoor Lobbies
Salsbury Industries 3505ARU Recessed Mounted Vertical Mailbox with 5 Doors and USPS Access, Aluminum
5-door recessed mount, aluminum, USPS access
Pros
- Sleek flush mount appearance
- Compartment is roomier than older models
- Solid aluminum build
- USPS approved
Cons
- Some units arrived with defective locks
- Keys occasionally do not work
- No doorbell mounting bracket
The Salsbury 3505ARU is the right pick when aesthetics matter as much as function. As a recessed vertical mailbox, it sits flush with the wall and gives a clean, modern look to apartment lobbies, condo entrances, and upscale townhome mailrooms.
The 5-door configuration serves a small building of 4 to 5 households. The aluminum construction is fully powder coated, available in aluminum, bronze, and sandstone finishes. The unit weighs only 8 pounds, making it the lightest in our roundup, but do not let that fool you into thinking it is flimsy. Reviewers describe it as solid and well-built.
One long-term reviewer noted that after more than a year of use, the unit still performed like new, with no corrosion or door sag. That is a strong endorsement for a recessed mailbox that lives indoors but is still subject to humidity and temperature swings in unheated vestibules.
What to watch out for
Quality control is the main issue. A small percentage of units arrive with misaligned doors or locks where the included keys do not work. Salsbury customer service generally resolves these issues, but the return process can be slow. Order from a Prime-eligible seller if you can.
One feature users wished for is a built-in doorbell mounting bracket. If your building has separate buzzers, you will need to install them adjacent to the mailbox, not on it.
Who should buy this cluster mailbox
Property managers and condo boards who want a recessed, flush-mount cluster mailbox for an indoor lobby. The roomy compartments and clean look are best for buildings where aesthetics drive the decision. Skip this if you need an outdoor or pedestal-mounted unit.
6. Salsbury 3504ARU 4-Door Recessed – Best for Tight Wall Spaces
Salsbury Industries Mailbox, 30 lb, Recessed, 3504ARU – 1 Each
4-door recessed mount, 30 lb capacity, keyed lock, aluminum
Pros
- Sleek flush mount design
- Quality hardware at fair price
- Strong customer service
- Solid aluminum construction
Cons
- Not USPS approved in all configurations
- Post office appointment required
The Salsbury 3504ARU is a 4-door recessed vertical mailbox designed for buildings that want a flush-mount look without the larger 5-door footprint. It measures 30 inch D x 8 inch W x 6 inch H, which fits in narrower wall cavities than most recessed units.
Reviewers consistently describe this as a sleek flush mount option that upgrades the appearance of older mailrooms. The aluminum body is fully powder coated, and the keyed lock design is consistent with other Salsbury recessed units in the 3500 series.
With 136 reviews and a 4.4-star average, this is a proven option for small multi-unit buildings. The 30 lb listed capacity refers to the per-compartment weight limit, which is more than enough for typical residential mail volume.
One important caveat: some configurations of the 3504ARU are not USPS approved depending on your local postmaster. Before purchasing, call your post office to confirm that the recessed 4-door unit is acceptable for your delivery route.
Customer service experience
Several reviewers mention excellent customer service from the seller, including fast replacement of defective units. This is a real plus if you are ordering for a property that needs to be operational quickly.
The 3-year limited manufacturer warranty is shorter than the 5-year warranty on the pedestal units, which is worth noting for long-term planning.
Who should buy this cluster mailbox
Buyers who need a narrow recessed mailbox for a 4-unit building, especially in a tight wall cavity. The flush-mount look is the main draw, paired with solid Salsbury build quality. Skip this if you need USPS approval certainty or a larger capacity.
7. Salsbury 3506ASU 6-Door Surface Mount – Most Popular Mid-Size Wall Unit
Salsbury Industries 3506ASU Surface Mounted Vertical Mailbox with 6 Doors and USPS Access, Aluminum
6-door surface mount, striated trim, 5-pin cylinder cam lock
Pros
- Professional appearance
- Easy to install
- Good value
- Quality aluminum build
Cons
- Cheap hinges on some units
- Poor compartment labeling
- USPS requires exact location match
The Salsbury 3506ASU is the most popular mid-size surface mount cluster mailbox in our roundup, with 115 reviews and a 4.3-star average. The 6-door configuration hits a sweet spot for 5 to 6 unit buildings that want more capacity than a 4-door unit without the cost of an 8-door.
The striated doors and trim are a thoughtful design touch. The grooves resist scratching during shipping and installation, so the unit arrives looking professional even after a long freight journey.
Each compartment is 5-1/2 inch W x 16-1/4 inch H x 6-3/4 inch D, which is generous for residential mail, magazines, and small packages. The 5-pin cylinder cam lock comes with 2 keys per tenant, and the surface mount design means installation is straightforward for anyone comfortable with basic tools.
The 56-liter total capacity is enough for 5 to 6 households with normal mail volume. The aluminum body weighs 12.1 pounds, which is light enough for a single installer to handle on a wall mount.
Common concerns from owners
The hinges on some units are reportedly thin and may come loose within a year. A few reviewers fixed this with stronger replacement screws, but it is a valid concern if your tenants will be opening and closing compartments frequently.
Compartment labeling is minimal out of the box. Plan to add your own number decals or printed labels, since the included marking is hard to read at a glance.
Who should buy this cluster mailbox
Property owners with 5 to 6 unit buildings who want a surface-mounted cluster mailbox that is easy to install. The 115 reviews make it a proven option, and the striated finish holds up well over time. Skip this if you have hinge durability concerns or need recessed mounting.
8. Salsbury 3505ASU 5-Door Surface Mount – Best for Replacement Projects
Salsbury Industries Mailbox, Aluminum, Powder Coated, 5 Doors, Surface, 3505ASU – 1 Each
5-door surface mount, powder coated aluminum, 5-pin lock, 2 keys
Pros
- Top-notch construction
- Perfect fit for replacement projects
- Nice color and finish
- Easy to install
Cons
- May arrive with dents in exterior
- Not for fully exposed outdoor use
- USPS approval process can be slow
The Salsbury 3505ASU is the cluster mailbox I recommend to property managers replacing an aging 4B+ standard unit with a modern USPS-approved surface mount. It carries a 4.6-star rating across 104 reviews, with consistent praise for top-notch construction and a perfect fit in standard wall openings.
The 5-door configuration is identical in footprint to the 4-door 3504ASU, but with one additional compartment. If you are upgrading from an old 4B+ unit and need one extra slot, this is the move. The powder coated aluminum finish is fully made in the USA, and the striated doors resist scratching.
The 23-pound shipping weight makes this a manageable single-person install on most exterior walls. Each compartment includes a 5-pin cylinder cam lock with 2 keys, and the 3505ASU is available in 3 to 7 compartment configurations if you need to scale up or down.
The 5-year warranty and consistent Salsbury quality make this a long-term replacement solution. Several reviewers noted that they replaced 20+ year old units with the 3505ASU and the upgrade in security and aesthetics was immediate.
What to verify before ordering
This unit is not designed for fully exposed outdoor installation. If your mail kiosk is uncovered and exposed to rain, snow, and direct sun, consider a pedestal CBU or add a protective overhang.
Some units arrive with cosmetic dents in the exterior casing, especially when shipped via LTL freight. Inspect the unit on delivery and document any damage with the carrier before signing.
Who should buy this cluster mailbox
Property owners replacing an older 4B+ mailbox in a covered mailroom, vestibule, or under-shelter installation. The 4.6-star rating and exact-fit design make this the easiest replacement decision in our roundup. Skip this for fully exposed outdoor environments.
Buying Guide: How to Choose the Best Cluster Mailbox?
Choosing the best cluster mailbox comes down to five decision points: capacity, mounting style, USPS compliance, security, and ownership responsibilities. Let me walk through each one based on what I learned from comparing 8 units and reading hundreds of real user reviews.
USPS STD-4C compliance and what it means
Since 2006, the USPS has required all new centralized mail delivery equipment to meet the STD-4C standard. This standard replaced the older STD-4B+ standard and sets minimum compartment dimensions, security requirements, and parcel locker ratios. Every cluster mailbox on our list meets STD-4C, which is the current USPS approval benchmark.
One important note: USPS approval is decided at the local postmaster level, not the federal level. I have seen situations where a perfectly compliant unit was rejected because the local post office wanted a different configuration. Always confirm with your local USPS branch before ordering.
ADA requirements for cluster mailboxes
The Americans with Disabilities Act requires that a portion of cluster mailbox compartments be within ADA reach range. Specifically, 4B+ and 4C standards require that at least 25% of compartments (but no fewer than one) be mounted between 28 inches and 67 inches from the ground. For wheelchair users, the bottom row of compartments must be reachable without bending more than 48 inches from the ground.
All Salsbury units in this roundup are designed to meet ADA reach range when installed on a standard pedestal or properly recessed wall. If you are designing a custom installation, verify reach heights with your local building inspector before pouring concrete or cutting wall openings.
Capacity planning for your property
The general rule is one compartment per residential unit, plus one parcel locker for every 10 compartments. For example, an 8-unit building needs 8 tenant compartments and at least 1 parcel locker. The 3308BLK-U and 3312SAN-U both exceed this with 2 and 1 parcel lockers respectively.
For properties with high package volume (modern apartment complexes with 50%+ package deliveries), consider doubling the parcel locker count. Salsbury offers standalone parcel lockers in matching finishes that pair with any CBU.
HOA responsibility vs homeowner responsibility
This is the most common point of confusion in forum discussions on r/HOA. The general rule: the HOA or property owner is responsible for the cluster mailbox unit itself, including the cabinet, locks, and parcel lockers. Homeowners are responsible for their individual compartment key and for reporting damage.
If a compartment lock fails, the HOA pays for rekeying. If a homeowner loses their key, the homeowner typically pays for a replacement. If the master Arrow Lock needs rekeying (which should happen every 5 to 10 years for security), the HOA coordinates with USPS.
Security features that matter
The two most important security features in modern cluster mailboxes are anti-pry latches and key capture systems. Anti-pry latches prevent thieves from using a flathead screwdriver to force open a tenant door. Key capture systems prevent unauthorized key duplication.
All Salsbury units in this roundup include 5-pin cylinder cam locks with anti-pry designs. The 3300 series (pedestal units) adds reinforced hinges and a heavier-gauge aluminum body. Forum users on r/homeowners report that 10+ year old Salsbury units with these features held up to break-in attempts, while older 4B+ units from other brands were pried open within minutes.
Climate and durability considerations
For coastal climates, the powder coated aluminum is the right choice. Steel alternatives corrode within 5 years in salt air. For mountain climates with heavy snow and ice, look for units with sloped tops and reinforced doors. The pedestal CBUs in this roundup all have flat tops, so you may need to add a protective cover or position the unit away from roof drip lines.
For hot desert climates, the black and dark bronze finishes can reach surface temperatures over 140 degrees Fahrenheit in direct sun. Consider sandstone, gray, or white finishes, which reflect more heat and stay cooler to the touch.
Installation basics
Pedestal CBUs require a poured concrete pad at least 6 inches thick and 36 inches square. Allow 24 to 48 hours of curing time before mounting the unit. Surface mount units need a structural wall with appropriate anchors. Recessed units need a wall cavity at least 6 inches deep.
All cluster mailboxes in this roundup require a USPS appointment to install the master Arrow Lock. This appointment can take 2 to 6 weeks to schedule, so plan your installation date well in advance of any move-in deadline.
Frequently Asked Questions
Does the USPS provide cluster mailboxes?
No. The USPS does not provide or sell cluster mailboxes directly. Property owners, HOAs, and developers purchase USPS-approved cluster mailboxes from licensed manufacturers like Salsbury Industries and Florence Corporation. After purchase, the USPS installs the master Arrow Lock at no charge to the property.
Which brand of cluster mailbox is considered the best?
Salsbury Industries is the most widely used cluster mailbox brand, with the broadest product line and strongest customer service. Florence Corporation is the second major manufacturer, often chosen for decorative and custom installations. Both brands meet USPS STD-4C standards and offer comparable security features.
What are the ADA requirements for cluster mailboxes?
Cluster mailboxes must have at least 25% of compartments (but no fewer than one) mounted between 28 inches and 67 inches from the ground. For wheelchair access, the lowest row of compartments must be reachable from a forward approach without exceeding 48 inches in height. Pedestal CBUs in this roundup all meet these requirements when installed on a standard pedestal.
How much does a cluster box cost?
Cluster mailboxes range from around $439 for a basic 4-door recessed unit to over $2,700 for a 12-door pedestal CBU with parcel lockers. The average pedestal unit for a small community of 8 to 13 homes costs between $2,500 and $2,800. Surface-mount and recessed units are generally less expensive than pedestal models.
Who is responsible for replacing cluster mailboxes?
The HOA or property owner is responsible for the cluster mailbox unit itself, including the cabinet, master locks, and parcel lockers. Homeowners are responsible for their individual compartment key. When the master Arrow Lock needs rekeying, the HOA coordinates with the local post office, which performs the work at no charge.
Final Verdict: Which Cluster Mailbox Should You Buy in 2026?
After six weeks of comparing 8 cluster mailboxes, reading hundreds of user reviews, and consulting USPS specification documents, my top pick is the Salsbury 3308BLK-U 8-Door CBU for most properties. It offers the best balance of capacity, security, and USPS approval, and the dual parcel locker configuration addresses the most common complaint from forum users about package theft.
For smaller properties on a budget, the Salsbury 3504ASU 4-Door Surface Mount delivers genuine Salsbury quality at less than half the cost, with 269 customer reviews backing the decision. For larger buildings that need maximum door height, the Salsbury 3313BLK-U 13-Door Type IV CBU earned the highest 4.9-star rating in our roundup.
Whichever cluster mailbox you choose, plan for the USPS master lock installation appointment before you set your move-in date. That single step is the most common source of delay in cluster mailbox projects, and a 2 to 6 week wait can derail an otherwise smooth installation.