A precision and try square, for both layout work and machinery set-up and checking. The stock and blade are hardened steel. Etched and black-filled for legibility, the 2 1/2" long blade is available in Imperial graduated in 32nds and 64ths, or metric with millimetre markings on one side and millimetre and half-millimetre markings on the other. The knurled nut accurately secures the blade in any position from full left to full right.