Description The item is a set of 200pcs simple and practical filter bio balls, which features plastic construction with high-perfomance stuffing, and is excellent for oxygenating your water and helping the gas exchange process. So they are great for any freshwater or saltwater fish tank or mini-reef aquarium. Features - Color: Black. - Material: Plastic and cotton. - Size: 2.6x2.6x2.6cm - Each ball size: about 2.6cm (diameter). - and Aquarium Fish Tank Filter Bio Balls Bio-Balls. - Each ball features plastic construction with high performance stuffing. - The Bio-Balls have a structure of dense holes where live a lot of nitro-bacteria. - 200pcs filter bio-balls excellent for oxygenating your water and helping the gas exchange process. - Great for any freshwater or saltwater fish tank or mini-reef aquarium.Package list: 200 x Bio Balls