Kryptonite keeper 12 std u lockthis is an affordable u lock made from 12mm hardened steel and vinyl coated so it protects your frame this should be used in conjunction with a cable lock to secure the entire bike as a leader in action sports security and the creator of the original bicycle u lock in the bicycle security category in 1971 kryptonite offers premium quality security products features an affordable u lock for moderate crime areas 12mm hardened steel shackle reinforced collar over