Mul-T-Lock HD1 Interactive Hercular High security deadbolt system for commercial and residential doors. Operation: 90° key rotation throws the bolt 1" toward the frame, interlocking two hardened ball bearing with the strike to increase jimmying resistance. Materials: Solid brass rings and cylinder, Hardened Steel bolt and anti drilling ring, Steel strike, Nickel Silver & Stainless Steel pins. Additional features: Suitable/Adjustable for two back-sets (2-3/8 or 2-3/4), no need for different parts. Easy conversion between standards and drive in. Supplied as standard with 1" throw. Thumbturn tail self-adjustable to door thickness. Cylinder Mechanism: Mul-t-lock unique, high precision telescopic pin tumbler system. Pick and drill resistant for high security needs. UL437 listed for burglary, UL fire rated bolt, ANSI Grade 1. Two Interactive plus keys included. Control card required to get extra keys made.