The KeyKeg Bag-in-Keg Technology is a laminated, hermetically sealed inner bag, which offers multiple layers of protection against light, oxidation and contamination. It maintains Keg shelf life through, for example, keeping beverages separate from the propellant gases used to dispense. That means any gas, such as compressed air, can be used to squeeze the bag and force the beverage out to almost the last drop. Compressed air is a cleaner, cheaper alternative to CO2, N2 or mixed gas.