KLOUD City &reg; Black 30" 75cm Fish Tank Aquarium Rubber Air Curtain Bubble Diffuser Tubing Black rubber soft air curtain, can be changed to any shape Pipe Diameter(Approx.) : 9mm/0.35"; Pipe Length : 75cm/29.5" Inlet Connector Inner Dia. : 2mm/0.08"; Inlet Connector Outside Dia. : 4/0.16" Helps improve water circulation, easy to install