Made to transfer the pressure from the thinnest part of the socket wall toward the thicker section, resulting in increased strength. Set contains the following sizes: 3/8", 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", 1-3/16", 1-1/4", 1-5/16", 1-3/8", 1-7/16", and 1-1/2 in deep length.