In my efforts to find an economic parking heater, I ended up first purchasing from another supplier. The product was broken, inaccurate, and a pain to deal with. Buying this unit from HappyBuy was much better. Fully functioning unit, an actual instruction manual, and came as listed.As far as function, I've only bench tested the unit so far, but it went exactly as anticipated. I followed tutorials from the internet for how to operate, and that made all the difference. I'm very excited to install this into my Cargo Camper and extend our camping season to year round.