This padlock has a closed shackle which is locked by a double ball bearing mechanism. Rotate key 60 degrees to unlock. Body is made from case hardened steel and shackle is made from hardened boron alloy steel. It is key retaining with drilling protection and protective shutter prevents dust contamination. Drainage holes prevent freezing and has black electrophoretic. Mul-T-Lock's unique high precision pin tumbler system results in a pick and drill resistant for High Security needs. Supplied with reversible nickel silver key with plastic key head and colored insert for identification.