13 piece set is made in the U.S.A., featuring an improved black coating retaining more rust preventative compound than black oxide. All the SK impact sockets feature the SK's SureGrip® hex design, which drives the side of the hex, not the corner. This not only provides increased strength, but also avoids the rounding of rusted or damaged fasteners, which can occur when using a sharp cornered hex tool. The neck-down design provides improved access over tapered design. The thin-wall design combined with 12 Point SureGrip® Hex Design makes these sockets perfect for heavy-duty applications when space is tight.Thin-wall design combined with 12 Point SureGrip® Hex Design makes these sockets perfect for heavy-duty applications when space is tightSureGrip® Drive Design drives the side of the fastener, not the corner, to provide increased strength and avoid rounding of rusted or damaged fasteners.3/4" Drive Thin Wall Impact Sockets - 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", 1-1/2"