A co worker picked one of these up a while back and has had some good feedback. We use it on hydraulic systems but the brochure says it’s good for air also. I’m real tempted on picking one up. They are quite a bit bigger than the average gauge but a few rifles have the space. I’m thinking of the bottom plug on an MK2 Rapid. https://phoenixsensors.com/products/wireless-pressure-transducer-weps04/