Chrome Vanadium steel Total Drive® sockets, hardened and heat treated for strength with a fully polished mirror finish for resistance to corrosion. Can be used on a wide range of fasteners. All are suitable for Spline, Metric Hex and Bi-Hex, with many also equivalent to TRX-Star*, Whitworth, Imperial Hex and Imperial Bi-Hex. Knurled ring for extra grip with greasy fingers. Supplied on rail.