It took me a minute to figure out why this adapter was wired in such a way that I had to connect positive to negative. I checked it with a multimeter, everything is fine. Cord, plug and polarity are assembled correctly, but the manufacturer should have labeled it better and explained why it is arranged the way it is. I think this is a good reminder to never trust these Chinese manufacturers and always check before connecting. No problems after installation. Charged my Jackery 240 with a 100W HQST panel with no problems. Easier instructions and better cable markings would have given it 5 stars instead of 4.