Our METAL mini-keg draft beer system uses large 16 gram CO2 gas cartridges held inside the unique tapper / regulator. Although the photo shows three kegs, this setup actually comes complete with 4 Mini Kegs to hold five gallons of beer (each keg holds 5 liters of beer), precision German metal tapper / regulator, reusable keg bungs, AND a box of 10 CO2 capsules. Just put your own home brewed beer in these kegs, and you’re good to go! (By the way, the German tapper has an adjustable regulator, so you can control the beer flow. Full pictorial instructions are included.