Used for marking out right angles and checking for squareness. The stocks are made of Rosewood, the blade from tempered, blued steel. They have a machined brass face for protection against damage and accuracy. The blade is secured by means of 4 brass diamond washer and steel rivet. The blade has also been chemically blued to help prevent corrosion. The rosewood stocks found on the carpenter's square result in an attractive tool. Manufactured to British Standard BS3322. The squares are tested on both the inside and outside faces, our specification for the internal angle is twice as accurate as that specified in the British Standard, an accuracy better than 0.01mm/10mm blade length. All TOOLMAN squares are tested during manufacture and prior to despatch. They are tested on both internal and external faces. the internal faces are accurate to better than 0.001" nominal size.