CR-MO alloy steel for long life. Lifetime warranty. Heavy duty blow molded storage case. Includes most common SAE sizes used for automotive repairs. SAE - inches: 1-5/16, 1-3/8, 1-7/16, 1-1/2, 1-9/16, 1-5/8, 1-11/16, 1-3/4, 1-13/16, 1-7/8, 1-15/16, 2, 2-1/16, 2-1/8, 2-3/16, 2-1/4.