uxcell Plastic Fish Tank Suction Cup Biochemical 2 Sponge Filter Air Pump Oxygen Tube Hole Diameter : 1.8cm/0.7" Sponge Size : 8.1 x 4.5cm/3.2" x 1.8"(H*D) Overall Size : 13.5 x13cm/5.3" x5.1"(H*W); This sponge filter uses bubbles of air from an external air pump, or an integral water pump to draw water through the sponge. Simply install an airline into the unit and provide both aeration and filtration for your fish