- The three largest tap sockets, also available individually, are now packaged in a three piece set- Ideal for use where a T-handle won't fit, especially in restricted areas- For larger, fractional M.C.T.I. standard taps- #9 socket is 5/8" (16 mm), #10 is for 11/16" (18 mm) and #11 is for 3/4"- Sockets contained in a vinyl holder