Tri-Wing Torsion Insert Bit.Tri-Wing Insert Bit No.4. 10 Piece Packs. 1.0 in. (25mm) Lengths Machined on 1/4 in. hex.Turned Down Torsion Style Shank. Precision Machined Exact Fit Tip.Natural Beaded Steel FinishThrough hardened for Maximum Durability.WIHA Exclusive CRM-72 S2 Modified Tool Steel.Guaranteed Quality Made In Germany.