you can call tech suppoet for harbor freight. The co2 will not replace argon but will work on a mig welding mild steel. The cheep migs do not weld aluminum very good , if you buy a spooler for the hand you might get by but your welds will never look very good on thin material, I am no welder but I fought the mig thing for a long time and finally brokedown and got a tig. I still have my mig although it is not a harbor freight model it is a 220volt 170 amp with gas , it still will heat up after welding quita bit and shut down till it cools would work good on car bodys but 16 gauge steel gives it a good workout. A freind has one of the 110v units it is almost good enough to throw across the room every 5 minutes