With OnGuard's Doberman Combo lock, all you need is your bike, the lock, and a number you can remember. This combination lock uses four numbers and can be reset any time. It's made from a strong steel cable covered with tough vinyl to protect both itself and your bike. The Doberman Combo is also self-coiling for easy transport. And the Glo model has a built-in micro light that backlights the numbers so you can see them in the dark! Genius!