Features : Super fine and high rate of CO2 diffusion. Simple install, mounted outside or directly to aquarium glass Suit for an inner diameter of 12mm/16mm/19mm and outer diameter of 16mm/22mm/25mm of water tubes. Buit in bubble counter and integrated check valve 3 sets outlets using safety nut design,to make the trachea and water pipes locked Specifications: Material: PE Ceramic Weight:250g 3 Set Nozzle Diameter: 12mm Inlet/16mm Outlet,16mm Inlet/22mm Outlet,19mm Inlet/25mm Outlet Package included : 1x Dissolution CO2 Diffuser