The OnGuard Bulldog 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 Z-Key cylinder with its pick-, pull-, and drill-resistant design plus an ultra-hardened steel shackle that's 13mm in diameter. Five keys are included, including one with a micro-light for ease of use when the sun goes down. U-lock's 13mm/0.51" ultra-hardened steel shackle provides maximum cut resistance U-lock's double bolt locking mechanism provides added strength and high pull resistance by locking tight to 2 sides of the bar Pick, pull, and drill resistant Z-Key cylinder with Bumpblok offers optimum deterrent against physical attack U-lock features 5 laser-cut keys (1 micro-light and 4 extra grip keys) Micro-light key projects a bright white beam for easy use after dark Double rubber coating on U-lock crossbar Quick release multi-position mounting bracket