Sponge filters provides the ideal location for bacterial colonization and the sponge traps larger waste particles mechanically cleaning the water without trapping baby fish. It quickly established a bio-filter and extra oxygen, two sponges means more surface area for beneficial nitrifing bacteria to colonize and faster cycling. Using an air hose to connect one end to you air pump and the other end to this filter. The pipe can be adjusted within 19.5 cm to 27.5cm in length, the filter boxes is 100ml in capacity, sponge is 4.8cm x 8.4cm is size, fit for 210 L aquarium in Max. Comes with 2 suction cups to stick to glass, can be installed anywhere,it can also be used as a prefilter or secondary filter.