The Ohmite RNS200 is a wirewound rheostat, a type of variable resistor used to control voltage or current in electrical circuits. These rheostats are designed for durability and precision, making them suitable for a wide range of industrial applications, including motor speed control, lighting dimming, and laboratory equipment. They are subject to mechanical wear and have a finite life. Models H, J, K, L and N are listed under UL File No. E-10946 and CSA File No. 21309.