We installed the Progressive Industries EMS-LCHW30 in our popup after a surge in a CG damaged our converter. In the years following the install it cut power twice while connected (low voltage) and indicated improperly wired power posts a couple of other times. We traveled 4-6 weeks each year for 5 years so the unit saw dozens if not hundreds of different connections. When we bought our Vibe last year a EMS-HW30C was the first purchase I made. They are easy to install, customer support is very good, the design is modular and others have shared that PI will help you troubleshoot a unit and sell you components as needed.
The readout, while not intended as a precision monitoring system, is wonderful. It displays voltage, amperage (which is very useful in monitoring the various systems in the camper), and frequency. The unit also delays reconnecting after a fault to prevent damage to air conditioners. I have no association with PI, purchased the first based on recommendations found on numerous forums and the units have not disappointed.