Features:
Great for fish tanks， to promote gas exchange and increase dissolved oxygen levels.
Great for tropical fish farms， koi ponds， waste water systems， etc.
For use with wet/dry filters (here is not included)， to improve biological filtration.
Aiding in the critical gas-exchange process that is needed for successful biological filtration. 

Specifications:
Color: Black
Material: Environmental Plastic
Quantity: 100pcs
Dia: 18mm / 0.7in
Package Size: Approx. 21 * 14 * 2cm / 8.27 * 5.5 * 0.79in (L * W * H)
Package Weight: 152g / 5.35oz

Package List:
100 * Bio Balls