75%Argon 25%carbodioxcide
I read that this is the most versitile gas for fab work, and is supposed to produce more consistant welds especially when not using new or clean steal. But the pure co2 is supposed to provide better pennetration, but the welds arnt supposed to be as consistant or clean. Its all about preferance and knowing what your going to be welding on. I use 75/25 and have had real good luck on a variety of metals...
