The uk39s biggest selling thatcham approved chain amp padlock this high security chain and padlock is made with a forged hardened steel lock body and a hardened steel 11mm shackle for maximum protection against attack the thatcham institute for vehicle security is recognised by insurers as the ukrsquos leading tester of vehicle security products products with the thatcham label have been demonstrated to comply with the british insurance industryrsquos criteria for vehicle security