Quickly access hard-to-reach fasteners in confined spaces using the 1/2 in. Drive 10 in. Impact Extension. This tool is designed for use with most drive tools, including fixed-head torque wrenches. A full chamfer at drive opening and a drive-end chamfer, with four detents, work to provide quick positive engagement consistently on socket drive walls. The two thru holes and groove are designed to accept a PROTO retaining ring, pin, or O-ring.