The Technical Research Corp. Surge Guard, at least the big one (about 300 dollars give or take) is supposed to be as good as the Progressive Industries in every respect save one.. Only a 1 year warranty.. PI is lifetime limited.
Does all the same thing.. few seconds different on the re-connect delay is all.
IT will protect against open neutral, ground, polarity issues, over/under voltage or frequency. Displays both amps and voltage and YES the voltage reading is not accurate.. Mine (When adapted to 30 amps) always I mean ALWAYS showed lower voltage on L-2