The spanner wrench is made specifically for our ER-16 spindle, which is assembled in our headstock. Use the ER-16 spanner wrench in conjunction with the 1″ hex wrench (P/N 65025, sold separately) to tighten and loosen the ER-16 collet nut.
The tool is cut from a 1/4″ steel plate and has a tough, black oxide coating to keep it from rusting.