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: TX30 Length mm: 50 Shank Dia. inch: 1/4 Shank Type: Hex Material: S2 Hardened Carbon Steel Timco S2 Driver Bits - TX (Size TX30 x 50 - 5 Pieces) in Grey