Kryptonite evolution s4 u lock 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 features14mm hardened max performance steel shackle resists cutting and leverage attacks double deadbolt locking mechanism for extensive holding power new higher security disc style cylinder with more than 1 million key variations reinforced anti drillpull cylinder protection system en