Value Packaging: You will get 100 pieces of biological porous filters with a diameter of 16 mm. High-quality materials: These organic filter ball filter media are made of high-quality plastic and sponge, which are environmentally friendly, safe, odorless, non-toxic, durable, reusable, and will not change water quality problems. Working principle: When water flows through the internal space, it extends the time and uses nitrifying bacteria to achieve the effect of biochemical filtration. Scope of application: 16 mm biological balls are very suitable for use in fish tanks, ponds and aquariums. Flexible and easy to use, can be added to water tank filters, top filters, fish pond filters or bottom filters, etc. Kind Tips: Customer satisfaction is our top goal! If you don't like the product or find that there are quality problems with the product, please feel free to contact us, We will do our best to solve the problem for you in a timely manner!