Tetra Whisper Bio-Bag Disposable Filter Cartridges MediumThese disposable filter cartridges are easy to use and work to help keep your fish tank in tip top condition. The ultra activated carbon is designed to remove discoloration, contaminants, and foul odors while the dense, double sided mesh works to trap debris and fish waste. Convenient and easy to use Keeps aquarium water crystal clear Removes odors and discoloration Dense dual sided mesh filters debris and fish waste Easy to assemble