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 Lock for Several Brands ILCO 1003M Keyway, Opens Counter-Clockwise with 90 Rotation, Nickel Finish (1 Set)
$9.75
This Prime-Line lock offers broad compatibility and a comprehensive kit with five cams, making it highly versatile for various mailbox types.
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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
$9.99
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.
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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)
$7.47
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.
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- ✅ 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...
- Super Value Set: Includes 6 sets mailbox lock. Each set includes 1 lock cylinder, 1 spring clip, 3 keys, 5 shaped locking tabs, 1 nut, and 1 gasket, providing everything needed for replacement
- Wide CoSecure & Reliable: Each mailbox lock with keys provides smooth operation and dependable locking performance to help protect mail and personal informationmpatibility: Designed as a reliable mailbox lock replacement compatible with L-1172C/C...
- Premium Material: Crafted from durable zinc alloy, this mailbox lock with key offers excellent corrosion resistance, strength, and long-lasting security for daily outdoor use
- Easy Installation: Simple structure allows quick mailbox lock replace without special tools—ideal for homeowners upgrading or replacing old mailbox locks
- Includes spring clip, mounting nut and (3) keys
- Does not include cam/latch
- C9100 operates clockwise
- Complete Mailbox Lock Replacement Set: Includes 6 mailbox lock sets, each with 1 replacement lock cylinder, 3 identical keys per lock, and 6 different cams (including the C7120 cam lock tongue). If multiple sets are purchased, each lock comes with its own...
- Wide Compatibility: Designed to fit a variety of mailbox models, this replacement mailbox lock provides reliable security and versatile compatibility for residential and commercial mailboxes.
- Premium Quality Construction: The L-1172C mailbox lock features a rolled nickel-plated finish for enhanced durability and corrosion resistance, helps improve mailbox security, tampering, and daily wear.
- Easy Installation: Mailbox locks with keys replacement replacing your old mailbox lock is quick and hassle-free. Simply remove the old lock and install the L-1172C C9100 replacement lock using the included mounting hardware and accessories.
- [Universal Mailbox Lock] Upgrade security in seconds! This universal mailbox lock is precision-engineered to fit any standard mailbox size and type. Comes with 2 keys and 5 adjustable inserts for a perfect, hassle-free fit.
- [Quick Installation – No Tools or Experience Required] Get your lock installed in minutes, not hours. Designed for DIY simplicity, our set includes everything you need. No professional help necessary—just secure your mailbox and enjoy peace of mind...
- [TWO-LOCK BUNDLE – Double Protection for Your Home] Get enhanced security and value with two complete lock sets in one purchase. Secure multiple mailboxes—or keep a spare for future use. Perfect for households with separate mailboxes or for gifting to...
- [Built to Last – Weather, Rust & Tamper Resistant] Constructed with durable, corrosion-resistant materials, this lock withstands daily use and harsh weather. Enjoy reliable performance year after year—it’s the last mailbox lock you’ll ever need.
- Ideal Use: Replaces lost, damaged, or worn mailbox locks on residential, community, and cluster mailbox systems
- Dimensions & Compatibility: Compatible with many mailbox brands including American Device, Auth-Florence, Bommer, and Miami-Carey; includes 5 interchangeable cams for versatile fitment
- Materials & Components: Durable diecast, brass, steel, and stamped steel construction with zinc-plated hardware, nickel-plated cylinder face, 5 cams, retaining clip, and 2 keys
- Key Features: Precision 5-pin tumbler lock with Hudson keyway and key-retaining design that prevents key removal while unlocked
- 【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...
- Super Value Set: Includes 3 sets mailbox lock. Each set includes 1 lock cylinder, 1 spring clip, 3 keys, 5 shaped locking tabs, 1 nut, and 1 gasket, providing everything needed for replacement
- Wide Compatibility: Designed as a reliable mailbox lock replacement compatible with L-1172C/C9100 mailbox lock, besides compatibility with a wide range of mailbox models
- Premium Material: Crafted from durable zinc alloy, this mailbox lock with key offers excellent corrosion resistance, strength, and long-lasting security for daily outdoor use
- Secure & Reliable: Each mailbox lock with keys provides smooth operation and dependable locking performance to help protect mail and personal information
- 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)
- 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.
This article is part of our complete guide Safety & Security — browse all our comparisons and buying guides.
Last update on 2026-10-15 / 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 Lock for Several Brands ILCO 1003M Keyway, Opens Counter-Clockwise with 90 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.
