Pencil Commstone: Medium, 3/8 in Overall Lg, 5/8 in Overall Wd, 6 in Overall Ht

Commstones, also known as commutator stones, are handheld abrasives that remove defects from motor commutators and slip rings. Flat spots, high spots, grooves, and ridges can be removed by manually applying the stone to the rotating parts of a running motor.