Check the listing for details. Tetra® Whisper Bio Bag Disposable Filter Cartridges available in 7 sizes. Condition: New. Listed at 12.41 USD. Tetra Whisper Bio-Bag Cartridge replacements complete the Whisper Power Filter package for a clean, easy-to-maintain aquarium. Filled with ultra-activated carbon, these ready-to-use disposable filter cartridges remove waste particles, odors and discoloration for crystal clear water. Genuine Whisper filter cartridge replacementsKeeps water crystal clearRemoves odors and discoloration Bio-Bag cartridges are tough on the debris that makes aquariums nasty. Ultra-activated carbon absorbs odors and discoloration and dense, dual-sided mesh catches debris and fish waste better than other brands to keep your fish tank clean. Replace cartridges once a month for maximum filter efficiency. Tip: Replace Bio-Bag cartridges when water begins to overflow excessively from the Wonder Tube chamber. Sizing: Small : Fits Whisper In-Tank Filter 3iMedium: Fits Whisper Power Filters 10i, E, J, 10 and MicroFilterLarge (formerly Regular): Fits Whisper Power Filters 20i, 40i, C, 20, 30, 40 and 60X-Large: Fits Whisper Power 4 and 5 Power Filters