Chrome Vanadium 6150 steel bits hardened to 52-53 HRC and tempered for added strength. Set includes 3/8"" and 1/2""Sq drive to 10mm hex Chrome Vanadium steel bit adaptors. Supplied in storage case with inclined tray for quick and easy bit selection. One of a comprehensive range of Premier Hand Tools, suitable for daily professional use. Chrome Vanadium 6150 steel bits, each size in 30 and 75mm lengths. Set includes 3/8"" and 1/2""Sq drive to 10mm hex Chrome Vanadium steel adaptors. Supplied in storage case with inclined trays for quick and easy bit selection. Contents: Security TRX-Star* Bits; T20H, T25H, T30H, T40H, T45H, T50H, T55H, T60H (1 each 30 and 75mm), Hex Bits; 4, 5, 6, 7, 8, 10, 12mm (1 each 30 and 75mm), Ribe Bits; M5, M6, M7, M8, M10, M12, M14 (1 each 30 and 75mm), Spline Bits; M5, M6, M8, M10, M12 (1 each 30 and 75mm), Drive Adaptors; 3/8""Sq x 10mm Hex, 1/2""Sq x 10mm Hex. Lifetime guarantee*.