A beer gas canister is very highly pressurised. This needs to be controlled when exiting the canister before it gets the keg and the rest of the system. This primary mixed gas regulator fixes directly to the gas bottle and can be adjusted so that the pressure is at the correct level. Different beers and ciders require different levels of pressure for them to be served at optimum quality. Pipework going from the regulator can then either go directly into the keg to push the beer out of through the product line and then through the rest of the the system, or if you are serving multiple products using the same gas you can use a fitting to split the gas line into the required number of lines and then feed those into secondary regulators so the pressure can be individually adjusted.