Irwin Tools 3514996C Screwdriving Insert Bit Set, Tamper-Resistant TORX (6-Pack), 6 Piece Forged from high-grade S2 steel. IRWIN bits are between 58 and 62 on the Rockwell hardness scale Tamper-resistant TORX screws feature a post in the center of the recess that will only fit into a tamper resistant TORX bit We manufacture a wide variety of point sizes to fit many different applications. All bits meet ANSI Standards Includes T10-TR, T15-TR, T20-TR, T25 TR, and T27-TR bits