The airhorn is connected to the CO2 regulator. I thought I would use the on/off feature but now I have it always on and turn the gas on/off with a shutoff valve on the regulator. In other words, the airhorn is not needed. I could have just put a short piece of racking tube in the stopper and the gas line on that. I use the airhorn because it fits in the quick disconnect on my gas line. The quick disconnect allows me to change from airhorn to air chuck to pin or ball lock disconnect rapidly.