DURATECH 10-Piece Impact Socket Set are constructed of heat treated chrome vanadium steel with a professional-grade, black phosphate finish for anti-oil, anti-rust, which is a type of alloyed tool steel with great strength and durability for high-intensity long-term work. Includes: 8 PCS SAE size sockets: 5/16, 3/8, 7/16, 1/2, 9/16, 5/8, 11/16, 3/4 inch. 2 PCS extension bars: 1/4” hexagon * 3/8” square. All these items are packed in a strong case.