Sherline 2255 Sherline Pair of RH and LH 3/8”Insert Tool Holders w/ 80° Inserts. Sherline now manufactures its own inserted tip carbide tool holders. hold-down screw and special Torx key. The 3/8" square shank is held in a P/N 7600 tool post. The tip of the cutting tool is .375" from the bottom of the holder, which is the industry standard. The holders are made from case hardened steel with a black oxide finish.