We have a great range of airsoft green gas and we also sell red gas and even black gas for airsoft guns. Green gas is the most commonly used gas propellant in bb guns. If you are buying gas for a pistol with a plastic body, this is the one you want as red and black gas could be too powerful for your gun and damage it. Green gas also has an amount of lubricant in it that will help keep your gun maintained. red and black gas are dry so they will eventually dry out your guns seals and could make your mag leaky.