Master Lock - (4) High Security Pro Series Keyed Alike Padlocks 6230NKA-4 w/ BumpStop Technology Four (4) High Security Locks Keyed Alike w/ 8 Keys. ProSeries Padlocks are designed for Commercial/Industrial applications. The same lock with a longer shackle is also available, search 6230NKALH. Comes with a Limited Lifetime Warranty. If you order two 4-packs they will NOT necessarily be keyed the same. To buy multiple 4-packs keyed alike you need to purchase the locks via fulfilled by MERCHANT - HOW TO FIND: When you look at the listing there is a link showing the Other Sellers on Amazon. This is under the "add to cart button". Look for the 4-pack fulfilled by Merchant LocksChocksTiedowns. If you purchase any 4-pack multiple we will automatically key all locks the same. These locks feature the BumpStop Advanced Cylinder Technology. (for explanation see more product details below). Dimensions: 2-1/2 (64mm) wide round solid steel body, each weighing 1.48 lbs. A 7/16 (11mm) diameter hardened boron alloy shackle with 1-1/8 (29 mm) inside height clearance. Chrome rustproofing provides longer life. These high security, rekeyable 5-pin cylinders with spool pins are virtually impossible to pick. And a dual ball bearing locking mechanism resists pulling and prying.