Ashcroft sprinkler gauges are designed for use on wet or dry sprinkler systems. The 3½” gauges are UL listed and FM approved. The SG1 is used in a dry system on the sprinkler head side of the control valve to accurately monitor line air pressure, with the ability to accept water pressure up to 250 psi (upon system activation). Custom gauge faces are available with your name and phone number. Call for more information.