Used for Fastening This ratchet socket wrench is a hand tool used for tightening or loosening fasteners such as nuts and bolts. You can keep the socket or fastener in place while moving the wrench to reposition it and get a better handling with the wrench. 10 Included Sockets This 3/8-inch / 10mm socket wrench includes 10 sockets set for most uses. The sizes of the sockets included are: 10, 11, 12, 13, 14, 15, 16, 17, 19, 22mm. The quick release handles let you easily swap and switch between sockets that fit your needs.