Beer kegs are typically made of stainless steel, although they can also be made of aluminum. Stainless steel is the more common material used for beer kegs. Kegs are designed to maintain the carbonation in a beverage by storing it with pressurized carbon dioxide in the headspace above the liquid. The liquid is also dispensed using pressurized gas. There are different types of stainless steel beer kegs available, and they generally follow a universal standard in the way they work. The most common type of coupling is the “clamp and twist” method, with the less common ones being “insert and twist” and “slide” methods.