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.

This key fits the flywheel side on the Vespa GS160 and SS180, VSB1T, VSC1T, VNX, VSX, VLX and Genuine Stella Length: 12.25 mm Width: 3.00 mm