If you always intend to mount your cut-off tool on the rear side of the part where it is out of the way and ready for use at all times, this accessory is a one-piece holder that takes the place of placing the P/N 3002 holder on top of the 3016 spacer, saving $15.00 in the process. The cutting tool is still placed in the holder upside down, and the wider base offers more support than the 3002/3016 combination; however, it can only be used on the back side of the part. Designed for use with Sherline tools only.