The Torx drive system meets industries demand for a reliable fastening system. It virtually eliminates slipping and screw head distortion. Alloy steel blades are heat-treated for strength and durability. T10 Part # 41473 T15 Part # 41474 T20 Part # 41475 T25 Part # 41476 T30 Part # 41477. Backed by Craftsman's Lifetime Guarantee!