The Black Bio Filter Sponge is a 45x45x2cm sheet of filter sponge made from durable and high-quality materials such as polyester and non-woven fabrics. This filter sponge is designed to trap dirt, debris and other particles in an aquarium. It is easy to install and maintain, and it is also effective in removing unwanted particles from the water. The filter sponge is also able to retain beneficial bacteria, thus creating a healthy aquatic environment. The Black Bio Filter Sponge is suitable for both freshwater and saltwater tanks, and it is an ideal choice for aquariums of all sizes.