This is an Ohm's Law double-sided calculator (an electronic and radio related slide chart), which was produced by the Ohmite Manufacturing Company of Chicago, Illinois in 1941. This bright yellow and orange piece measures 4" wide by 9.25" long and is made of stiff cardboard with grommets at each corner. On one side, the scales compute ohm's law along with voltage and wattage up to 1000 ohms. On the other, the scales compute the 1000 ohm to 10 megohm ranges. Instructions are printed on each side. In generally good condition with some minor surface wear and edge staining.