A professional quality heavy duty 21mm scaffolders impact socket. Manufactured from high strength toughened Chrome Molybdenum (Cr-Mo) steel for increased durability and longevity. Black Phosphate finish for corrosion resistance. Specifically designed to handle the nuts and bolts used in constructing scaffolding. The socket has a 21mm 6Pt hex head and a standard 1/2″ square drive for use with an impact driver. Retaining pin and ‘O’ ring included. Length of 52mm.