The Colombo CO2 advance set contains a pressure cylinder with 95 gram CO2, a pressure regulator, a 3-in-1 diffusor and all connections. With the pressure regulator the flow of CO2 gas to the diffusor can be adjusted. A bubble counter is incorporated in the diffusor, by counting the bubbles released in a specific time frame the amount of CO2 added can be determined. The diffusor produces very fine bubbles so the gas is well absorbed by the water