Shipwright, If you have the Handler 125, it is plumbed inside for the gas, and all you need is the bottle with gas, a gauge, and some hose. I found a flow gauge at a surplus place for a few bucks, and I just use some cheap plastic hose for it. I'ts been working for me now for about 10 years. If you have a pressure gauge, you'll have to play with the pressure to get the weld you want. If you have a flow gauge, it's easier. I also used a quick disconnect fitting like that on an air compressor on the back of my Handler so that I can easily disconnect the gas to transport. The gas you use for steel is 75% CO2 25% Argon. For Aluminum you will need 100% Argon. I use the .023 wire for body work and it works well. You will need to get the .023 tip too. I used one like this
regulator until I found my flow gauge like this one:
flow gauge Good luck, once you try mig, you'll probably never go back to flux core.
John.
