These Faithfull Hexagon Sockets are professional, high quality metric sockets, forged from chrome vanadium steel which is hardened, tempered and satin chrome plated for corrosion protection. 1/2 inch square drive is the most popular drive size used in the UK, due to its strength and durability. Faithfull sockets have a hexagon design that gives an accurate fit on both nuts and bolts and the chamfered end allows easy nut location and entry.The FAISOC1221 Hexagon Socket has the following specifications: Drive: 1/2 inch square. Size: 21mm Hexagon.