This Square D Pumptrol 9013GHG2J51R Square D Pumptrol pressure switch has a 200/250-psi pressure sensor size for direct control of electrically controlled air compressors and water pumps. This diaphragm-actuated switch has contacts that open on rising pressure, enabling an adjustable activation range of 100-80 psi operating points. The switching points set with an adjustable screw nut and are drift proof. The National Electrical Manufacturers Association (NEMA) 1 enclosure has a rugged polyphenylene oxide and steel housing for long life and includes a flange with a 1/4" NPSF internal fluid connection. The switch must be mounted in the vertical position to maintain its enclosure rating. Three knockouts are provided for wiring flexibility. The mechanical components are covered with a Chromate 3 plating for corrosion resistance in compliance with Restriction of Hazardous Substances (RoHS). The switch contacts are reverse action/two N. O. contacts.