BSP Electronic Commutator Timer tool.

The BSP com timer allows you to easily and accurately measure the comm advance on all armatures. To measure an arm, simply rest two poles of an arm on the flat surface. The shaft slides inside the dummy comm, and using the lever ease the comm round until the slot on the dummy com and the arm line up. The digital read out gives a clear indication of comm advance. The tool is powered from your power supply and uses approx 9v.