This listing is for EIGHT (8) padlocks keyed alike (same key unlocks all) and sixteen keys. The lock is also available with Bump Stop Technology. Search 37NKA in our storefront. APPLICATION: These padlocks are ideal for all outdoor applications when needing multiple locks that utilize ONLY one key. The #37 latch lock works well on 1-7/8 and 2 inch couplers and on virtually all standard hasp applications. These locks have a removable shackle sleeve. Sleeve off - Secures coupler latches. Sleeve on - Works best with hasps. KEY RETAINING - ensures that padlock is not left unlocked. PADLOCK FEATURES: 1-9/16"(21mm) wide x 3"(76mm) high. Armored Shackle Guard blocks bolt cutters. Revolving, case-hardened steel shackle sleeve resists cutting and sawing. Removable shackle sleeve. Sleeve off - Secures coupler latches to accommodate openings 9/32" (7mm) in diameter. Sleeve on - Works best with hasps, fits openings 1/2" (13mm) in diameter or larger. Precision pin tumbler mechanism resists picking. IMPORTANT NOTE: If using this style lock on a trailers coupler latch please be aware it is NOT recommended for all 2-5/16 couplers. It will fit some 2-5/16 couplers, the exception being 2-5/16 couplers that have the latch partially recessed from the top surface of the coupler, or latches that are wider than 7/8. ATTENTION: If you order two 8-packs or any multiple of this lock they will NOT automatically be keyed the same. To receive 16 keyed alike you will need to order direct from the merchant LocksChocksTiedowns also available here on Amazon.