This 4000 PSI gauge is not a cheap paintball gauge, it's designed for heavy-duty industrial use with high-pressure air, gases and hydraulics. It's a perfect upgrade for all PCP and HPA airguns that operate up to 4000 PSI. We use these for all our custom PCP and HPA airgun builds. A 15/16" six-point socket fits perfectly, an adjustable wrench can also be used. It measures 15/16" from flat to flat and 1" from point to point with a nickel-plated brass case and 1/8 NPT male center-back connection. Thread tape or sealant (not included) is required for installation. We suggest using the military-grade thread tape we have listed.

The cover and dial face can be removed by using a standard air compressor to blow air into the vent-hole on the back of the casing, do this with the gauge pointed into a bag or box to safely catch the parts which will blow-off with considerable force. The dial plate can be placed with the needle in whatever position you want to adjust the pressure reading, or if there's no pressure, the middle of the box below the first line (as shown in the photo) is the standard position. A tiny drop of super glue is used to keep the dial face from rotating out of position. The cap snaps back in place, use a flat surface like a table top to push it on flush and even with the casing.