The Ohmite RHL20K is a wirewound rheostat, a type of variable resistor commonly used in industrial applications for controlling voltage or current. These rheostats are known for their durability and precision, making them suitable for a wide range of control systems. They are subject to mechanical wear and have a finite life. Models H, J, K, L, and N are UL and CSA listed. All rheostats have a 10% tolerance.