You have a few options for monitoring the air pressure in your air system. We stock Dakota Digital gauges and Viair analog gauges.
With the Dakota Digital gauges, you can "T" in a pressure sensors anywhere in the circuit to each air bag and in the air tank, and then run a supplied wire from each sensor to the gauge.
With the Viair analog gauges, they come in single needle or dual needle. If you have separate circuits for each air bag (which you should) we recommend 2 dual needle gauges, one for front and one for rear, and a single needle gauge for the tank pressure. They are 2" diameter, and are available in 160psi or 220psi, white face or or black face. With analog gauges you need to run a small air line to each gauge.