Metric Roofing Square 400 x 600mm This Stanley Steel Metric Roofing Square, 400 x 600mm, is designed for roofing calculations and layout of stairs, its face is graduated every 2mm, and on the reverse of the blade every 1/8 inch for detailed work. It has a reversed reading scale and crisply embossed graduations for easy reading. This square has buffed finish and has a protective lacquer coating for rust resistance. Specifications Width 400mm (15.3/4in). Length 600mm (23.2/3in).