16mm hardened MAX-PERFORMANCE STEEL SHACKLE resists bolt cutters and leverage attacks Patented*HARDENED STEEL SLEEVE over crossbar for double security DOUBLE DEADBOLT locking for extensive holding power HIGH SECURITY DISC-STYLE CYLINDER Center keyway defends against leverage attacks Protective vinyl coating SLIDING DUSTCOVER protects and extends cylinder life 3 STAINLESS STEEL KEYS - one lighted with high intensity LED BULB & REPLACEABLE BATTERY Key Safe ProgramPatents 6397648, 6430975