The Moore & Wright Engineer's Squares have a precision ground blade and stock and a blind riveted construction. The blade has been hardened and tempered for longer life. Conforms to B5939/Grade B.The Moore & Wright 4003 Engineers Square Grade B 75mm (3in) has the following specification: Blade Size: 104.8 x 25.4mm.Stock Size: 68.5 x 25.4mm.Inner Working: 49.3 x 79.4mm.