Features: 【Application】The 71670 large tap socket set fits larger fractional M.C.T.I. standard taps, 5/8 in. through 3/4 in. They also fit 16mm and 18mm metric taps manufactured to M.C.T.I. standards. The set is ideal for use in areas where a T-handle just won’t fit. 【Work with Extension】These sockets allow users to tap threads in tight or hard-to-reach areas. Used with a standard ratchet, T-handle, or extension, making the set highly compatible with a range of tools. .