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 – one LED lighted key with replaceable battery and 2 new, ergonomic ‘I” keys. Durable Weather-resistan nylon sleeve prevents scratches. Key Safe Program. Product dimensions: 21.5” (55cm) chain length.Product weight: 4.40 lbs (2.00 kgs).