Applications ---Aquarium Filter Cotton The thick layer captures excess substances and activated carbon, absorbs heavy metals, etc., providing clean and clear water. A hanging cotton in the aquarium, effective aquarium wall filter accessory for aquariums promotes their overall well-being. Easy to change ---Aquarium filter for aquariums The filter core is easy to use, they are user-friendly and can be easily installed without the need for complex modifications or tools. Simply rinse with cold water to remove the toner and insert it into the filter compartment, and it can be replaced in seconds. High-quality materials --- The aquarium filter sponge is made of cotton, which has good water absorption, good air permeability, strong cotton texture, and soft hand feel. 6 pieces of hanging cotton for aquariums, easy to install and remove, ensuring clean water in the aquarium. Reusable --- The aquarium filter mat is easy to clean, captures residues, fish waste, odors, and discoloration, etc., and you can use the aquarium filters for fish and rocks repeatedly. Helps you save materials. It replaces aquarium filter cartridges and absorbs harmful bacterial impurities for fish, to keep the water source clean. Size information --- Aquarium filter cartridge 135 x 55 mm, This aquarium filter replacement is perfect in workmanship, can perfectly replace the original replacement. Suggest replacing the filter cartridge every 2-4 weeks. Suitable for saltwater tanks, freshwater tanks, and aquatic tanks.