Exceeds ANSI Grade 1 standard for auxiliary locks. Solid brass, free turning collar and 1/4 inch diameter mounting bolts resist wrenching, prying and hammering attacks. 1 inch throw hardened steel bolt resists sawing and crowbar attacks. Hardened steel inserts and rotating pins provide drill and pick resistance according to UL 437 standard. The Medeco3 design offers a utility patent that provides protection against unauthorized key duplication.