10mm six-sided chain links made from 3T MANGANESE STEEL Patent-pending END LINK DESIGN secures chain to hardened deadbolt eliminating critical vulnerability HIGH SECURITY DISC-STYLE CYLINDER is pick and drill resistant Patented, reinforced OVAL CROSSBAR LOCK HEAD SLIDING DUSTCOVER protects and extends cylinder life 3 STAINLESS STEEL KEYS Durable WEATHER-RESISTANT nylon sleeve prevents scratches