Tamper-proof screws as described by their name are screws that are difficult or nearly impossible to remove without having the unique tool and/or bit fitted to the type of security screw drive being used. Types of tamper-proof drives include Torx security, spanner (Snake Eyes) security, and One-Way slotted. Types of head styles include truss head, flat head, button head and hex head and security screws are mostly available in 18-8 stainless steel SS.