16mm hardened MAX-Performance steel shackle resists bolt cutters and leverage attacks * Higher security disc-style cylinder * Double deadbolt locking for extensive holding power * 3 keys - one lighted with high intensity bulb & replaceable battery * Includes Transit FlexFrame Bracket for easy mounting to frame tubing 25mm to 80mm wheter round, oval, triangular, or square. Also features 360° rotation providing the ability to better fit and align with a bike frame"s specific geometry.