If you dread keys, the Shackleton is the ticket. You can program in your own four digit code for easy opening each time. Silicone overmold and quick, push button release shackle will protect your bike in most environments. Security rating: 5, 12mm hardened steel shackle, durable 4 DIGIT customizable combination, attack resistant, heavy duty combination wheels, 3. 75" x 6. 7"