TheKryptonite Messenger Mini Lock has a 11mm hardened MAX-Performance steel shackle provides a lighter weight lock while maintaining the security level of Evolution Minis. Kryptonite Messenger Mini Lock Features Increased shackle dimensions allows for a wider range of lock up scenarios Reinforced cuff over crossbar and cylinder for additional security High security disc-style cylinder is pick and drill resistant New patent pending bentfoot double deadbolt design New rotating dust cover with stopper plug 2 stainless steel keys with coiled wrist key chains Key Safe Program Rated 7/10 on Kryptonite's security scale