The Faithfull Engineers Square has been carefully crafted from high quality tool steel, these squares are accurate to BS939 Grade B standard. The stock and blade are precision ground to ensure straightness and accuracy, and the spring steel blade is hardened and tempered for increased durability. Size: 100mm (4in) External size: 120 x 75mm Internal size: 100 x 56mm Stock thickness: 8.5mm Blade thickness: 1.7mm FAIES4