Your underwater companions deserve a clean and fresh aquarium on a daily basis. This is easily achievable with Grreat Choice's Internal Filter Cartridges. Featuring a 3-way filtration to help keep water clean, your aquatic friends will swim, play, and rest with the comfort of knowing that they're well taken care of. Only at PetSmart. Features: 3-way filtration to help keep water clear, Activated carbon to promote purification Intended For: Aquariums Includes: (2) Filter Cartridges Size: Available in sizes for 10-gallon and 20-gallon aquariums Important: Read and follow the enclosed guide before replacing the cartridge in your filter. Cautions: This is not a toy. Keep out of reach of children. Directions: 1. Open the filter chamber. 2. Remove the filtration basket. 3. Remove the adjustable valve. 4. Remove the used filter cartridge. 5. Rinse the new filter cartridge under cool water to remove dust. 6. After rinsing, fold the filter cartridge into a triangle shape. Inset it into the bio frame and then into the filter chamber. Make sure the frame fits completely into the filter chamber. Size: 10 gal.