A Woodruff key is a semicircular shaped, removable key that fits into a matching keyway cut into a shaft, leaving a protruding tab. The tab mates with a matching slot on a device mounted flush upon the shaft e.g. a pulley, thus preventing the device from freely rotating about the shaft.

Fits clutch on smallframe scooters V5A,V9A,VMA

Fits flywheel on GS 150's VS1-VS5