Features:Mini size is ideal for small fish tank.Can be also used as auxiliary filter for big size aquariums after linking with oxygen pump(Not included).No need extra electricity, can be driven with an oxygen pump.Easy to split box and clean.3 suction cups on the bottom.Washable activated carbon and cotton.Functions:Activated Carbon: improve the water quality of the fish tankCotton Filter: absorb the residual dirt, resolve fish feces quicklyQuartz Sand: obstruct a large number of fine particles in waterIncrease the solubility of oxygen in the waterBubble stone ejection of fresh air will lead to clean waterHow to use:Received a pump vent holes, directly into the fish tank applySize: 8 x 8 x 8cmPackage:1 x Mini Aquarium Filter.