S2 Steel is premium quality alloy steel for exceptional strength and durability compared with standard chrome vanadium driver bits. S2 grade hardened steel for longer life" Driver Bit Size: TX25 Length mm: 25 Shank Dia. inch: 1/4 Shank Type: Hex Material: S2 Hardened Carbon Steel Timco S2 Driver Bits - TX (Size TX25 x 25 - 10 Pieces) in Grey