Features: 1. Rational combination: Bio-Balls do not require replacement unless damaged or destroyed, Use scientific method, reasonable filter material, the filter media works better. 2. Effective: Resolve impurities,Stabilize PH,Clarify your water naturally. 3. Work as a biological filter media: Aquarium bio filter is excellent interaction between air and water and air exchange. They will promote air exchange and increase dissolved oxygen levels. So as to form a good ecological cycle. 4. Hollow Out: There is a hollow in the middle of the biological column filtering medium, can provide an anaerobic environment, reducing the content of nitrates in water, and promote more healthy water quality. 5. Great for any freshwater or saltwater fish tank or aquarium. Easy to wash and clean. Notice: 1. Actual color may be slightly different from the image due to different monitor and light effect. Please allow 1-3cm deviation due to manual measurement. Specification: Type: Aquarium Filter Media Main Material: glass, ceramic, stone etc. Style: includes 12 styles Include: 1 pack x 12-in-1 Aquarium Filter Media with storage bag includes: 1 pack x 12-in-1 Aquarium Filter Media with storage bag Our products are made with the highest quality materials and are designed to provide you with the best possible user experience. We strive to ship out all orders within three days of purchase, and the estimated delivery time is 8-4568 days. When shopping, please pay attention to the size and dimensions of the product to ensure that it meets your needs. In the title and , we have provided detailed information about the product, including its features and specifications We want you to be completely satisfied with your purchase, so if you have any questions or concerns, please don't hesitate to contact us. We are here to help and will do our best to assist you. Thank you for choosing our product. We hope you enjoy it!