We have one, very happy with it. It has shut down power to my rig when it was over 135v at the pole and when it was 103v at the pole. I have seen on other forums an installation using twistlock connectors to make it easy to uninstall.
I have had surgeguard (prior rig) and can tell you this was the first thing installed on my new trailer. The progressive unit has a long history of good performance and
after sale support. I can personally confirm their prompt and effective support. No affiliation just extremely satisfied customer.
