ISTA UFO CO2 Diffuser (S) ceramic silicon suction cup aquarium plants Atomizer Specific ceramic applied to assures most delicate CO2 diffusing effect. Top quality design allows the replacement of the diffusing ceramic; therefore eliminating the clogging problem. CO2 pipe can be fastened to the diffuser in a vertical position. This way, it prevents the pipe from bending which restricts the flow of CO2. Elegant in design. To have the best diffusing effect, place the diffuser in the very bottom of the tank, which will maximize the CO2 diffusion in water (creates more contact time of CO2 bubbles with surrounding water) The silicon suction cup assures long lasting function. For 4/6mm co2 tube (Does not contain)