The Blue Spot Tools Impact Spline Bits are manufactured from S2 Steel for increased durability and strength. This set includes the most widely used spline sizes and are ideal for removing and applying spline fittings. The bits are heat-treated, hardened and tempered. They can be used with ratchets, breaker bars and air tools. This 9 piece set includes the following sizes: M6, M8, M9, M10, M12, M14, M16 and M18.Additional Information:• Drive Size: 1/2in• Type: Spline• Socket Type: Spline• Range: M6-M18• No. Sockets: 9