Here's a Shinko Electric type BJ-3 5-013 24 VDC clutch. It was intended for use in a copier or printer. In use, the clutch would mount on an flatted 8 mm shaft at the coil end. The coil case would be fixated using the tab near the bottom of the case. Energizing the clutch locks the gear to the drive shaft. Other modes of operation are possible by adding a sprocket or gear to the clutch face at the center ring. The operating voltage is not critical- it worked fine with a 12 volt supply when we tested it. The gear is a left-hand helical with 30 teeth, 29.8 mm diameter, 8 mm face width. Unused.