The Sensata Dominican RP10A is a thermal protector for lighting fixtures. It has a dedicated voltage 220Vac. The Sensata Dominican RP10A has thre leads color coded for proper installation. When the temperature of the fixture is exceded it will cause the light to blink. It is auto resetting for when the fault is corrected. The Sensata Dominican RP10A is designed to fit into a 1/2" KO.