Hardened and tempered for longer life. High-quality chrome vanadium steel, ball end design allows for angle access in tight areas. Packaged in reusable plastic holder. Includes sizes: 5/16", 1/4", 7/32", 3/16", 5/32", 9/64", 1/8", 7/64", 3/32", 5/64", 1/16", and .05".