Sherline End Mill Set, single-ended end mills can be held in a mill collet or a 1/4" end mill holder. Their small size makes them useful where space is limited. The set is made up of the highest quality general-purpose 3-flute cutters manufactured in the miniature series. Sizes are 1/8", 3/16", and 1/4" shanks. End mills must run true in order to cut properly. Small end mills or miniature size end mills are very expensive and can be easily damaged if milling is attempted using a drill chuck to hold the end mill. Milling collets or an end mill holder are a must for proper operation of you mill! Note: Use of cutting fluid is recommended.