Electro-hydraulic pressure switches are devices, which, when set under pressure close or open electrical contacts. They are widely used in applications where it is intended that, once a pre-set pressure is achieved and exceeded, an electrical switching command or signal should be triggered for further working cycles. Many different versions (with pressure setting on a dial, with main and secondary switch, screw-on pressure switches) enable their use in many applications. There is a design related difference of 8 ... 20 % between the upper switching point and the lower switching point. Only the electronic pressure switch type DG 5 E gives provision to select two independent switch points. Type DT is an analogous pressure sensor.