Answer: rheostats

AnswerCrossword Clue
RHEOSTATSCurrent regulators.
RHEOSTATSLight-regulating devices
RHEOSTATSCurrent regulators
RHEOSTATSDimming devices
rheostatsRHEOSTAT, a resistor used to control electric current
rheostatsAn electrical instrument used to control a current by varying the resistance