This is a bicycle lock. You can set the combination yourself. To change the numbers, move the knob inside the lock towards you (photo 3), then you can change the numbers (photo 4). Push the knob away from you (photo 2) to set the combination. When in use, keep the knob pushed away from you (photo 2). It's hardly been used, but there are scratches on the plastic parts. It's still usable, so I'm offering it to someone.