1Used for upper filtration, bottom filtration and external filtration of fish tank. 2Biochemical ball body porous structure, water flow in the dense gap constantly changing the direction of water flow to prolong the water flow time, creating a working time for the cultivation of nitrifying bacteria, achieving sterilization and filtration 3Compact size, widely applications range, and can be used with other filters. 4The bio balls provide biological filtration, removal of toxic ammonia and nitrite. 5Great for fresh or saltwater aquarium filtration systems. Features:1.Used for upper filtration, bottom filtration and external filtration of fish tank.2.Biochemical ball body porous structure, water flow in the dense gap constantly changing the direction of water flow to prolong the water flow time, creating a working time for the cultivation of nitrifying bacteria, achieving sterilization and filtration effects.3.Compact size, widely applications range, and can be used with other filters.4.The bio balls provide biological filtration, removal of toxic ammonia and nitrite.5.Great for fresh or saltwater aquarium filtration systems.Specifications:Material: PlasticColor: blueSingle Size(length x width): Approx. 1.6x1.5cm/0.6x0.59inPacking List:1 Bag x Filter Bio Ball(100 pcs)