Dwyer Instruments 1800 Low Differential Pressure Switch for General Industrial Service Set Points from 0.07" to 85" w.c., Repetitive Accuracy within 2%, Series 1823 Pressure Switch. UL and CSA listed, FM approved, conduit enclosure removed to show electric switch. Essential for industrial environments, the Series 1800 combines small size and low price with 2% repeatability for enough accuracy for all but the most demanding applications. Set point adjustment inside the mounting stud permits mounting switch on one side of a wall or panel with adjustment easily accessible on the opposite side. UL and CSA listed, and FM approved. CAUTION: FOR USE ONLY WITH AIR OR COMPATIBLE GASES.