1/4" x 9/16" x 1-1/4" Zinc Plated Steel #21 Woodruff Keys WKS-171 (4 pcs.)
Diameter 2: 9/16"
Nominal Size: #21
Type: Woodruff Key
Box of 4.
A woodruff key or half-moon 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. It is widely used in machine tools and in the automotive industry.