I foolishly did not purchase the gas conversion kit when it was available, so had to make up my own later. The red hose feeds the gas from the solenoid valve to the welder's (Tweco) handpiece. The Sol. valve coil is 12VDC, so a resistor of equal value (coil resistance) was added in series so it could function on the "switched" 24VDC power supplied by the trigger. The resistor is shown directly behind the terminal block. I made a drive wheel to fit .025 wire and presenltly use it as a dedicated MIG brazer. If you are interested in Silicon- bronze wire, see here:http://www.awisco.com/migwelding.ht ml