About the ER-16 spanner set
The Sherline ER-16 Collet nut spanner set includes two wrenches. One has a pin that engages one of the holes in the Sherline spindle to keep it from turning while the nut is tightened. The other is a hex wrench that is sized to fit the special ER-16 nut (nut not included). This eliminates the need to come up with the proper size metric wrench and a Tommy bar when loosening or tightening the ER-16 collet nut. The pin tool provides better grip in your hand and better leverage than the Tommy bar. The tools themselves are cut from 1/4″ steel plate and have a tough black oxide coating to keep them from rusting.