Even if you are using commercially purchased carbonated beverages you still need a source of CO2 to push the liquid out of the kegs and through the taps. The larger the gas source the cheaper the gas is but the heavier and less portable. The mini regulators come with a sodastream adapter so you can use that option. The mini regulator can also use the 16g or 25g bulbs below and they come with an adapter to use a 2.6kg / 6kg refillable bottle (You will need to source these locally as we can't ship them).