The OnGuard Bulldog Combination Standard U-Lock provides superb peace of mind when it comes to securing your bike. This full-sized U-lock features all the protection features that makes OnGuard a stalwart bike security such as the steel ball click-combo gear system providing superior protection from pick and pull attacks plus an ultra-hardened steel shackle that's 13mm in diameter. The user-settable, 4-digit combination design means there's no keys to lose or forget for added convenience. U-lock's 13mm/0.51" ultra-hardened steel shackle provides maximum cut resistance U-lock's steel ball click-combo gear system offers superior protection from pick and pull attacks U-lock features 4-digit combination so there's no keys to lose or forget Double rubber coating on U-lock crossbar Quick release multi-position mounting bracket