SHURFLO GAS OUT FITTING - 1/4" BARB
This fitting is rarely used. It fits in the end of the pump and allows you to attach a gas venting hose to the pump.
If you need to vent the CO2 gas to somewhere other than the immediate area (inside a vending trailer, etc.) then use this fitting and attach hose.
The O-Ring base is 3/8" diameter.