Master Lock – Ten (10) High Security Pro Series Padlocks 6121NKALJ-10 w/BumpStop Technology
Price: $262.37
(as of Oct 21, 2025 18:14:28 UTC – Details)
FEATURING BumpStop TECHNOLOGY – Lock bumping a surprisingly simple method of breaking in through locked doors and padlocks – is undoubtedly the newest emerging threat to personal property security. And virtually all locks in use today are particularly vulnerable to bumping. Until now. BumpStop Advanced Cylinder Technology employs an innovative, patent pending design which utilizes a unique reverse rake tapered driver pin, high performance springs and tightly machined cylinder chambers. During a bump attempt, this design prevents the transfer of force from the bump key to the pins and therefore blocks rotation of the cylinder so that the lock remains locked.
This listing is for ten (10) High Security Keyed Alike Padlocks w/ 20 keys. ProSeries Padlocks are designed for Commercial/Industrial applications. Limited Life Time Warranty. The same lock is available with two shorter shackle lengths, search 6121NKALF and 6121NKA.
If you order two 10-packs or any multiple of this lock we will automatically key them all the same.
These locks feature the BumpStop Advanced Cylinder Technology. (for explanation see more product details below).
DIMENSIONS: 2-1/8 wide heavy steel body. A 5/16 diameter hardened boron alloy shackle with 2-3/16 inside height clearance.
Ideal for harsh outdoor conditions – exclusive Pro Series Weather Tough cover protects lock from water, ice, dirt and grime. Solid iron shackle shroud resists harsh physical attacks. The removable cylinder can be replaced or re-pinned. 5 spool pin tumbler cylinder for added pick resistance. Dual ball bearing locking mechanism resists pulling and prying.
Customers say
Customers find these padlocks to be of great quality, with one noting they’re a step above normal Master Locks. They appreciate the weather protection, with one customer mentioning they’re perfect for outdoor conditions. The lock strength and weight receive mixed feedback from customers.





