RJ Series 50W Rheostats (Potentiometers) Wirewound From Ohmite, the RJ series of rheostats has been designed and manufactured to retain high reliability and smooth operation over long periods of use. These rheostats are constructed from a ceramic body with resistance alloy winding and a vitreous enamel coating (or silicone ceramic coating depending on model). RJ rheostats have a metal spring contact arm, metal graphite composition and feature solder coated terminals. Product Applications: Suitable applications include motor speed controls, equipment requiring variable resistance settings and dimmer switches.