The 27 mm Seachem Beetle Diffuser is a highly effective way to disperse CO2 throughout your aquatic system. The pollen-style diffuser is compatible with 6 mm (1/4") standard airline tubing and connects directly to CO2 injection systems. The unit boasts a 27 mm large surface area disc that provides diffusion for large volumes of CO2 gases, helping to provide mid-sized and higher growth aquaria with the CO2 that they need to remain healthy and functional. Suction cups included with the unit. We suited for aquariums between 20-50 gallons.