6" x 12mm W/X2 Hex Chain with Lock * The Quattro Bolt Locking Mechanism provides unequaled strength by locking the cross bar to the shack * The new user friendly, pick, pull, and drill resistant OnGuard M-key Cylinder offers optimum deterre * OnGuard provides 4 keys and 1 Microlight key for night-time use * Register your key code. If you lose your keys and you have registered them, or know your key number,