Herga (PresAirTrol) Side Spout Spa Pump Air Switch, SPDT, 21A, 2 HP at 250 VAC, 1 HP at 125 VAC, ARA111A is an air operated switch used on older hot tubs and spas, to activate hot tub pumps. PresAirTrol SPDT switch is single pole, double throw, with a mic