Manufactured from chrome vanadium steel. Hardened & tempered for strength & durability. Ball ended for use at an angle of up to 25o where access is restricted. Set is supplied in a. Clip holder for convenient storage & contains sizes 5/64, 3/32, 1/8, 5/32, 3/16, 7/32, 1/4, 5/16 & 3/8\"."