The oil pressure sender is a sealed round canister with a pipe thread connection on one end and a single electrical connection on the opposite end. The pipe thread size is most often 1/8 inch NPT. The electrical connection is most often a 10 x 32 threaded post with nut and washer fastener. The function of this sender is to provide a variable resistance as the measured pressure changes, which in turn, modulates the current flowing through the connecter gauge. Inside the canister is a diaphragm which seals the oil from the electrical components. As the oil pressure increases it pushes the diaphragm outward from the oil chamber forcing a wiper arm to move across a variable resistance surface that is connected to the exterior threaded post electrical connection.
Gauge manufacturers are not standardized on the resistance of the senders so it is most important to select a gauge and sender combination from the same manufacturer to obtain the correct operation and accuracy.
All oil pressure senders look similar and there is no way to tell the pressure range and resistance from the outside. You must physically measure the pressure vs resistance of a given sender OR have knowledge of the manufacturers part number and sender specification. Our senders are matched to our gauges.