Double sided plastic calculator, made by Fearns, Mear & Co, 43 St Helens Rd, Huddersfield, c1960.
The calculator uses imperial measurements only, and is 19cm in diameter, with one rotatable disc each side. The first side is for rolled steel sections and the second for cylinders, plates, tubes and bars. The instructions for use are given on each side. It has a heavy duty dark green cloth-covered card slip case.
Both the calculator and the slip case are in excellent condition with no signs of wear. A fascinating piece of recent industrial history.