OnGuard's Bulldog STD LM boasts an 11mm-thick, hardened-steel shackle and OnGuard's stout X2 double-bolt lock that resists drilling, picking, bumping, and pulling for serious protection. And thanks to the included mounting bracket, you can bring the Bulldog along for every ride. This great U-lock also comes with five keys, including OnGuard's Microlight key which has a built-in light. - Dimensions: 4.5 x 9 inches - All OnGuard locks feature integrated covers for protection from moisture and dirt. - OnGuard locks feature plastic, rubber or vinyl at all contact points to protect your bike's finish.