Valken Green Gas is perfect for gas blowback airsoft pistols and rifles, providing hard hitting power while also keeping your gas-operated airsoft gun well lubricated.  Valken Green Gas, which is more powerful than HFC 134a gas, is best used in gas blowback airsoft pistols and rifles designed to operate with higher pressure gas (most airsoft gas blowback airsoft guns).  This green gas provides your gas airsoft gun with powerful recoil, smooth cycling, and a faster muzzle velocity! Most airsoft gas guns are designed to specifically use green gas for optimal operation.  Using propane with a silicone adapter can lead to uneven amounts of silicone oil being distributed into your gas airsoft gun, which may cause increased wear over time.  Valken Green Gas already has silicone mixed into the gas, providing a constant and even dispersal of lubricant.  Most airsoft gas gun manufacturers recommend or require the use of green gas with their high performance gas blowback airsoft guns due to its increased efficiency and consistent lubrication. – See more at: http://www.airsoftmegastore.com/11245-valken-tactical-12-pack-airsoft-8-oz-green-gas-gbb-case-41543.aspx#sthash.yRoM4xoZ.dpuf