For air and smoke gas, for overpressure (air) and differential pressure (air/air) with hose connection (1/4" for overpressure and 1/8" for underpressure), switching point can be adjusted with hand wheel.
Pressure switch Kromschroder DG500UG-3 With manual reset,, DG..H switches and locks at rising pressure DG..N switches and locks at falling pressure Datasheet