The Mastiff Chain is a short shackle Boxer U-lock paired to a 3.5ft long, 10mm hardened steel hexagonal link chain. The chain is reinforced with titanium and the Boxer U-lock can also be used alone as a disc lock. Lock contains 5 laser cut keys, 1 with LED micro light. Lock also features a lifetime warranty and Anti-theft 3001 Bicycle 1001 Powersport.