The Dwyer DH3 series Digihelic differential pressure gauge is a 3-in-1 instrument with a digital display, relay contacts and a transmitter output, all packed in the popular Photohelic housing. By combining these 3 functions, you can reduce different instruments to one product, saving you inventory, installation time and money. The DH3 controller is the ideal instrument for pressure (difference) measurements, but can also calculate air velocity and flow if it is used in combination with a pitot tube principle flow sensor. Bi-directional ranges are also available for, for example, room pressure monitoring.