The unit I received was not working properly and was returned after I contacted Revain Technical Support for help. The low price lured me in, and then a piece of junk made me uncomfortable. The output frequency and voltage were unstable from the start. Even at a very low load, which was 10% of the nominal operating power, the voltage dropped to around 90 volts after a few minutes. This unacceptable voltage drop was a problem as I didn't want to damage my electronics (wireless camera, radio and phone charger).