Mailbox locks are essential for safeguarding personal mail, documents, and packages from theft and tampering, providing peace of mind for homeowners and businesses alike. They are typically used as replacements for lost keys, broken mechanisms, or to upgrade security on existing mailboxes and, in some cases, file cabinets. Products were evaluated based on keyway compatibility, included components, ease of installation, material durability, user reviews, and feature analysis.
Prime-Line S 4140 Mailbox Lock – Replacement, Multipurpose Mailbox Lock for Several Brands – ILCO 1003M Keyway, Opens Counter-Clockwise with 90º Rotation, Nickel Finish (1 Set)
This Prime-Line lock offers broad compatibility and a comprehensive kit with five cams, making it highly versatile for various mailbox types.
Search on AmazonMailbox Lock Replacement - Universal Mailbox Locks with 4 Keys - Easy to Install Mail Box Lock and Key Set - Durable and Secure Lock Replacement with 4 Keys for Almost All Locking Mail Boxes
The VIXAVI lock stands out for its universal design and emphasis on quick, fuss-free installation, appealing to users seeking a straightforward, cost-effective solution.
Search on AmazonPrime-Line S 4573 Mailbox Lock – Replacement, Multipurpose Mailbox Lock for Several Brands – NA-14 Keyway, Opens Counter-Clockwise with 90º Rotation, Nickel Finish (1 Set)
The Prime-Line S 4573 is constructed from robust materials like diecast, brass, and steel, indicating superior durability and long-term reliability for demanding use.
Search on AmazonLooking for the best Mailbox Locks?
Discover now our comparison of the best Mailbox Locks. It is never easy to choose from the wide range of offers. On the market, you will find an incalculable number of models, all at different prices. And as you will discover, the best Mailbox Locks are not always the ones at the highest prices! Many criteria are used, and they make the richness and relevance of this comparison.
To help you make the best choice among the hundreds of products available, we have decided to offer you a comparison of the Mailbox Locks in order to find the best quality/price ratio. In this ranking, you will find products listed according to their price, but also their characteristics and the opinions of other customers. Also discover our comparisons by categories. You won’t have to choose your products at random anymore.
- REPLACEMENT LOCK – This multipurpose Prime-Line replacement mailbox lock is an easy fix and can easily replace lost or broken mailbox locks. Features 5 cams and an Hudson 1003M key
- WORKS FOR SEVERAL BRANDS – This replacement mailbox lock works with several brands of mailboxes, including: American Device, Auth-Florence, Bommer, and Miami-Carey.
- INCLUDES – Replacement lock kit includes a total of 5 zinc-plated steel cams, brass pins, a spring steel locking clip and 2 keys.
- LOCKING SECURITY FEATURE – This lock has a security feature that prevents the key from being removed when in the unlocked position, which prevents forgetting the key, and ensuring the mailbox is locked every time it’s used.
- NOTE – This mailbox lock unlocks by turning the included keys in a in the counter-clockwise direction and has a retaining hex nut and retaining clip
- ✅ Universal Mailbox Lock: Now you don't have to replace your entire mailbox to add an extra layer of security. Our mailbox replacement lock is carefully engineered to fit any mailbox size or type, and comes with 4 keys and five different sizes of locks.
- ✅ Quick & Fuss-Free Installation: No handyman skills? No problem! You can quickly install your new mailbox lock set yourself in minutes without complex tools or professional help. Upgrade your mailbox's security and enjoy that much-needed peace of mind.
- ✅ The Last Mailbox Lock You Will Ever Need: Built with reliability and long-term durability in mind, our rust-resistant mailbox key lock will handle daily wear and tear without skipping a beat, ensuring your mailbox remains functional for years to come.
- ✅ Protecting Your Mail Has Never Been Easier: Prevent theft or unauthorized access to your mail with our secure mailbox lock, which is both skid- and destruction-resistant. Keep your private documents and deliveries safe with an ultra-secure mail box...
- ✅ Sleek & Modern Design: Boasting a modern aesthetic that combines style and functionality, this mailbox lock replacement kit will take your mailbox's overall appearance to the next level. Add a touch of elegance to your mailbox today with our stylish...
- 【Bulk Value & Universal Compatibility】 The most cost-effective solution for property managers, HOA, and landlords. Precision replacement for L-1172C and C9100 locks. This multi-pack offers significant savings compared to buying individual units...
- 【Keyed-Different for Multi-Tenant Security】 IMPORTANT: Each lock in this pack has its own unique key set (3 keys per lock). Keys are NOT interchangeable between different locks. This ensures maximum privacy and security for multiple tenants or...
- 【Complete Professional Hardware Set】 Each individual lock comes with its own full accessory kit: 1x Cylinder, 3x Keys, and 5x Multi-Spec Cams. With a total of 5/10 sets included, you’ll have enough variety to fit multiple mailbox brands and door...
- 【High-Efficiency Batch Installation】 Streamline your maintenance work! Designed for rapid, tool-simple installation (5 mins per lock). No locksmith needed. Replacing old, rusted locks in bulk has never been easier, saving you hours of labor and high...
- 【Heavy-Duty & All-Weather Reliability】 Built with premium nickel-plated alloy steel for long-term outdoor use. Rust-proof and UV-resistant, these locks are engineered to handle the wear and tear of high-traffic apartment mailboxes while maintaining...
- Includes spring clip, mounting nut and (3) keys
- Does not include cam/latch
- C9100 operates clockwise
- Premium material: the cam locks keyed alike is made of excellent metal material made of zinc alloy, which is wear-resistant, corrosion and rust resistant, sturdy and durable for long time use.
- Easy to install: easy to install. Simply drill a hole in suitable place, insert lock head, fix tongue with fixing screw. Can be installed on metal, wood, doors, drawer panels, etc.
- Safe and reliable: the toolbox locks with keys provides you with sufficient security. Help protect privacy, assets and important materials and provide you with a safe personal space.
- Wide applications: suitable for sliding doors, cabinets, drawers, tool boxes, filing cabinets, mailboxes, furniture, RV compartments, vehicles and more. Drawer locks with keys are an extra security for important small items like documents.
- Versatile design: with 16mm cylinder length and strike plate, it can be adjusted to material thicknesses up to 12mm. This is a standard size lever lock with a diameter of 18 mm. Each mailbox lock is equipped with two identical keys to prevent one of them...
- REPLACEMENT LOCK – The U 9940 multipurpose replacement mailbox lock is an easy fix and can easily replace lost or broken mailbox locks. This is a 5-pin tumbler lock.
- WORKS FOR SEVERAL BRANDS – This replacement mailbox lock works for several brands of mailboxes, including: American Device, Auth-Florence, Bommer, and Miami Carey.
- INCLUDES – Replacement lock kit includes a total of 5 zinc-plated steel cams, brass pins, a spring steel locking clip and 2 keys.
- LOCKING SECURITY FEATURE – This lock has a security feature that prevents the key from being removed when in the unlocked position, which prevents forgetting the key, and ensuring the mailbox is locked every time it’s used.
- DURABLE, STRONG CONSTRUCTION – Made of diecast with a brass-plated face, this replacement lock is strong and durable, sure to last the test of time.
- New style C9100 USPS postal mailbox lock manufactured by Compx/National.
- File Cabinet Lock Set: you will get 24 pcs mailbox lock replacement, 48 pcs lock plates (2 types of lock plates included) and 24 pcs same keys, it will satisfy your one time purchase needs
- Size Information: cylinder length is 5/8"(16mm), fits up to 0.4"(10mm) panel thickness, this replacement cabinet locks can be installed on metal or wood, doors and drawer fronts; Please see picture for more detailed dimensions
- Zinc Alloy Material: mailbox lock is mainly made of zinc alloy, has strong precision casting, chrome plating surface, anti-oxidation process, solid casting, fine craftsmanship and reliable quality enable you to use for many years
- Easy to Install: these tool box locks are simple structure and easy to install, which provide you a quick way to solve the cabinet lock installation of problem, protect your belongings, provides extra security for your small items and drawers
- For safe use: These locks are designed for cabinets, drawers, and mailboxes. As with any metal part, some edges may feel sharp. Please handle with care during installation and do not allow children to play with the locks or keys
- Made in United States
- S 4140 Mailbox Lock Replacement, Multipurpose Mailbox Lock with keys for Several Brands – ILCO 1003M Keyway, Opens Counter-Clockwise with 90º Rotation, Nickel Finish (10 Set)
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Last update on 2026-03-31 / Affiliate links / Images from Amazon Product Advertising API
How to Choose the Best Mailbox Locks
Understanding Keyway Types and Rotation
When selecting a mailbox lock, the keyway type and rotation direction are critical compatibility factors often overlooked. Different lock manufacturers utilize distinct keyway profiles; for instance, Prime-Line offers models with both ILCO 1003M and NA-14 keyways. In practice, selecting a lock with the correct keyway ensures that existing spare keys, if any, might be compatible or that the lock itself can be rekeyed by a locksmith more easily. Furthermore, locks operate with either a clockwise or counter-clockwise rotation to unlock. The Compx National C9100, for example, operates clockwise, while many Prime-Line models, like the S 4140 and S 4573, are designed for counter-clockwise rotation with a 90º turn. Mismatching this can lead to frustration during installation and operation.
Assessing Included Components and Completeness
The contents of a replacement mailbox lock kit can vary significantly, directly impacting the ease and completeness of your repair. A comprehensive kit, such as the Prime-Line S 4140, typically includes multiple zinc-plated steel cams, brass pins, and a spring steel locking clip, offering flexibility to fit various mailbox designs. In contrast, some options, like the Compx National C9100, explicitly state that the cam/latch is not included, meaning you might need to reuse your old cam or purchase one separately. The VIXAVI universal lock, while stressing ease of installation, bundles its lock with four keys, providing ample spares. Evaluating what's included upfront prevents additional purchases or compatibility issues down the line.
Material Construction and Long-Term Durability
The longevity and security of a mailbox lock are heavily influenced by its material construction. Locks built from robust materials are better equipped to withstand environmental elements and resist tampering. The Prime-Line S 4573, for instance, is constructed from a combination of diecast, brass, and steel, which typically translates to a highly durable and corrosion-resistant product. Similarly, the VIXAVI universal lock emphasizes its rust-resistant properties and long-term durability. In practical terms, opting for locks with solid brass pins or zinc-plated steel components, as seen in various Prime-Line offerings, tends to offer a more reliable and secure solution compared to locks made from lesser quality alloys, which might degrade faster or be easier to compromise.
Pros & Cons
Prime-Line S 4140 Mailbox Lock – Replacement, Multipurpose Mailbox Lock for Several Brands – ILCO 1003M Keyway, Opens Counter-Clockwise with 90º Rotation, Nickel Finish (1 Set)
Pros
- Includes 5 zinc-plated steel cams for broad compatibility with various mailbox designs.
- Features a common ILCO 1003M keyway, potentially simplifying key duplication.
- Multipurpose design works with several popular mailbox brands.
- Opens counter-clockwise with a standard 90º rotation.
Cons
- Specific keyway and rotation might not be universal for all older mailbox models.
- Installation might require some understanding of cam selection.
Mailbox Lock Replacement - Universal Mailbox Locks with 4 Keys - Easy to Install Mail Box Lock and Key Set - Durable and Secure Lock Replacement with 4 Keys for Almost All Locking Mail Boxes
Pros
- Marketed as a universal lock, designed for broad compatibility across many mailboxes.
- Promises quick and fuss-free installation without requiring special skills.
- Constructed with rust-resistant materials for enhanced durability.
- Comes with 4 keys, offering multiple spares.
Cons
- The 'universal' claim might not cover every niche mailbox design.
- Specific material breakdown beyond 'rust-resistant' is not detailed.
Prime-Line S 4573 Mailbox Lock – Replacement, Multipurpose Mailbox Lock for Several Brands – NA-14 Keyway, Opens Counter-Clockwise with 90º Rotation, Nickel Finish (1 Set)
Pros
- Built with durable materials including diecast, brass, and steel for enhanced longevity.
- Works with most brands of mailboxes, offering good versatility.
- Features a specific NA-14 keyway, which is common in certain mailbox types.
- Opens counter-clockwise with a 90º rotation, a common operational standard.
Cons
- The NA-14 keyway is less common than ILCO 1003M, potentially limiting keying options.
- Only one set of keys is typically included, unlike some kits with more spares.
Common Mistakes to Avoid
Ignoring Keyway Type and Compatibility
A frequent error users make is failing to match the existing keyway type of their old lock or considering the common keyways in their area. For instance, Prime-Line offers locks with both ILCO 1003M and NA-14 keyways. Attempting to install a lock with a different keyway can lead to incompatibility with existing keys or make future rekeying more difficult and costly. Always verify the keyway type before purchase to ensure proper function and potential integration with other locks.
Overlooking Lock Rotation Direction
The operational direction of a mailbox lock is a crucial detail that often gets overlooked. Some locks, like the Compx National C9100, operate clockwise, while many Prime-Line models (e.g., S 4140, S 4573, U 9940) require a counter-clockwise 90º rotation to unlock. Installing a lock with the incorrect rotation for your mailbox's mechanism can result in the lock not functioning correctly or even damaging the internal latching components during use.
Assuming All Kits Include Cams
It's a common misconception that all replacement mailbox lock kits are complete with every necessary component. However, some products, such as the Compx National C9100, explicitly state that they do not include the cam/latch. This means users might need to reuse their old cam, which could be worn or damaged, or purchase a compatible cam separately. Always check the 'includes' section to confirm that crucial components like cams, clips, and mounting nuts are part of the package, as seen in the comprehensive Prime-Line S 4140 kit.
