The product consists of 100 pieces of simple and practical biofilter beads, which have a plastic construction with a high performance cotton filling and are ideal for the oxygen supply of your water and gas exchange .Equipped with a mesh bag to store these bio balls. Function: The bio ball aquarium filter media that helps clean your water in a natural way. Good to use in different types of filters, promote the growth of biological colonies and provide the most suitable living environment for your fish. Ideal for tropical fish farms, koi ponds, sewage systems, etc. For use with wet/dry filters (here is not included), to enhance biological filtration. Assist in the critical gas exchange process which is necessary for successful biological filtration.