Titan Tools 16039 13-Piece Tamper Resistant Impact Star Bit Set includes (2) bit holders and (11) bits. Sizes for 1/4-Inch drive bits are TR8, TR10, TR15, TR20, TR25, TR27, TR30, and TR40. Sizes for 3/8-Inch drive bits are TR45, TR50, and TR55. Set includes (1) 1/4-Inch and (1) 3/8-Inch drive bit holder and a convenient magnetic storage rail. Handy magnetic rail sticks to ferrous metal surfaces. Bits are constructed of S2 alloy steel for strength and durability. Torsion bit design allows bit shaft to withstand high torque by flexing under stress, reduces pressure on bit tip, and extends the impact life cycle up to 10x. Use of torsion bits reduces damage to fasteners and results in less stripping. Bit and socket set is made in Taiwan.