IRWIN 3053029 Insert Bit, T40 Drive, Torx Drive, 1/4 in Shank, Hex Shank, S2 Steel                     Tamper-resistant Torx screws feature a post in the center of the recess, this post will only fit into a tamper-resistant Torx bit. Used in applications such as control panels, display cases, high-tech equipment, security, 1/4 in hex shank.