【Cleanable and Reusable】Fish tanks biological filter media balls is cleanable and reusable, comes with a mesh bag for cleaning the filters every 3 months. 【Practical and Efficient】With multiple pores, it makes the water change its moving direction to prolong the time for cultivating nitrifying bacteria. 【Widely Application】This aquarium filter balls is suitable for both freshwater and seawater, can be used with other accessories, applicable to various kinds of fish tanks and aquarium.Package list:1 x Box of Biological Filter Media 1 x Mesh Bag 【Clean Water】Aquarium filter media can helps clean your water naturally and cultivate beneficial bacteria with these Polypropylene Bio-balls. 【Safe and Durable】This aquarium filter balls is made of plastic, safe, non-toxic, durable, won't change the water quality. It can help to create a nice living environment for water creatures.