High quality chrome-molybdenum alloy steel. Lifetime guarantee. Extra large markings for quick identification. This 13 piece set contains: 7/16", 1/2", 9/16", 5/8", 11/16", 3/4", 13/16", 7/8", 15/16", 1", 1-1/16", 1-1/8" and 1-1/4". Molded storage case.