uxcell Aquarium Fish Tank Airline Tubing Suction Cup Holders 20mm Dia 7 Pcs Black Material : Silicone;Color : Black;Package Content : 7 Pcs x Aquarium Airline Holder Fit Airline Diameter : 20mm / 0.8";Suction Cup Diameter : 38mm / 1.5" Good suction, can be used for aquarium and any glass surface. You can adjust air line length and shape according to your demand with this suction cups. Fits for 20mm standard air line.