One end opens telephone box fasteners, the other end tightens nuts on binding-post terminals. The 7/16 socket has a black finish and the 3/8 socket has a silver finish. Sockets are 1-1/4 (32 mm) deep to fit over long binding posts and are thin-walled for easy access into tight areas. Socket ends are color-coded for quick identification of socket sizes. Hex-socket design enables using a wrench to obtain extra torque. Sockets are heat-treated, alloy steel. High-impact, break-resistant handle for long and dependable service.