Here is a rare IWA made slide rule. Specially produced for Dutch Company WEMO. They specialized in machines for metalworking. The slide rule calculated weight per / mm on rolls of steel strips as well as length. All in good working order with some signs of use and age. It measure 13 x 13 cm or 5 x 5 inches. Check the attached video on how to work your vintage man tool : slide rule operation instructions!