Astro 78815 3-Piece 1/2-Inch Drive Dual Function Deep Tire Impact Socket Set Patented dual function design allows sockets to be used as Standard Sockets or 360-Degree Swivel Universal Sockets Sizes Include: 17, 19, 21mm 1/2-Inch Drive Hollow deep impact socket design creates room for removing longer bolts These sockets are 25-Percent-30-Percent more durable than traditional counterparts