All of the gauges in our range are electronically sensored. The sensor will either be reading for changes in temperature or pressure and the resistance of the sender will change with respect to changes in temperature or pressure. This resistance changes the current level in the signal wire hence changing the reading on the gauge.
All gauges with the exception of the air/fuel ratio gauge come supplied with the relevant sensor required for the gauge. The gauges are also supplied with instructions and securing connections for use if sinking into the dash.