This is a round gauge, with a metal case. It is inserted into the gauge panel via a 2 1/16 diameter hole. It is clamped into place from behind the panel face with the supplied metal back clamp, nuts and washers. The gauge face is black with white markings and a silver colored metal pointer. The pointer travels from left to right over approximately 60 degrees of arc with a range of 0 psi on the left and 100 psi on the right. This gauge is designed to be used on engines with a 12 or 24 volt dc battery system. The trim ring around the face of the gauge (the bezel) is polished stainless steel. The gauge is not illuminated.
The switch gauge functions in two ways:
1) provides a visual display of the engine oil pressure. The gauge requires that a pressure tube be connected to the oil pressure gallery of the engine from the 1/8 npt back connection on the gauge.
2) provides for an engine shut down when the gauge pointer contacts an adjustable contact on the face of the gauge. This connection forms a switch to ground circuit connecting the electric connection on the back of the gauge to the appropriate connection on the shut down relay. The case of the switch gauge must be wired to Battery Negative to complete the circuit correctly. This contact set point is visible and adjustable from the face of the gauge and is pre set to 20 psi.