United Electric 120 Differential Pressure Switch - 1 SPDT Switch Output. Adjustable Range: 3 to 30 PSID. Working Pressure: 30" HgVac to 100 PSI; Proof Pressure: 180 PSI. Deadband: 0.3 to 1.5 PSI. External Adjustment via Reference Dial, Single Conduit, Brass Bellows, Nickel-Plated Brass 1/4" NPTF Pressure Connections. Epoxy-Coated Diecast Aluminum NEMA 4X Enclosure for Class I, Div 1 and Class II, Div 1 Use