A3000-50MM is a A3000 Photohelic® pressure switch/gauge functions as versatile, highly repeatable pressure switch combined with a precise pressure gauge employing the time-proven Magnehelic® gauge design. The Photohelic® switch/gauge measures and controls positive, negative or differential pressures of air and compatible gases. Two phototransistor actuated, DPDT relays are included for low/high limit control. Easy to adjust set point indicators are controlled by knobs located on the gauge face. Individual set point deadband is one pointer width - less than 1% of full-scale. Set points can be interlocked to provide variable deadband - ideal for control of fans, dampers, etc. Gauge reading is continuous and unaffected by switch operation, even during loss of electrical power. Typical applications include air conditioning systems, clean rooms and fume exhaust systems.