Review on Camco Brass Water Pressure Regulator with Gauge - Safeguard RV Plumbing & Hoses from High-Pressure City Water - Easy-to-Read Gauge, Lead Free (40064) by Joe Vazquez

So this particular item is three times larger than the plain version without the cheap sensor. This is a pressure gauge with a cheap plastic ring and no pressure markings. In the fine print I finally noticed that it said "For external use only". The reason for this is that the "regulator" will let water through when over pressurized like a pressure relief valve. You don't want that in your cab or RV. For intended use, this probably works well enough if you don't mind wasting water. My city water is over 70psi and so this 50psi cutoff thing is dripping a lot of water due to the excess 20psi.