Green Gas is a propellant commonly used as the pressurized power source for various Airsoft related weaponry, and typically consists of propane gas with a small amount of silicone oil added for lubrication purposes. Green Gas is a popular propellant in the Airsoft community, but limited availability of the product has led many Airsoft players to create their own derivatives using retail propane and silicone oil (The mixture is then administered using specially made propane adapters). Product names of Green Gas typically vary from "Green Gas" to "Ultra Blow Back Gas" or similar, though they are all inherently the same type of Green Gas propellent.
As most Airsoft players have noted that propane and silicone oil constitutes the majority of Green Gas propellant, manufacturers have produced adapters that attach to propane tanks that are available at many retail stores, usually including reservoirs to store lubricant (usually silicone oil). The propane option has become popular in that the solution is cheaper in the long run than Green Gas, as well as being more widely available compared to Green Gas. Experienced players have noted that with the propane option, however, lubrication quantities should be noted in different temperatures as decreased lubrication in propellant is detrimental to the highly sensitive mechanisms of gas Airsoft weapons.