Penn-Plax Filt-a-Carb Replacement Activated Carbon Media ...

Penn-Plax presents the Filt-a-Carb Replacement Activated Carbon Media Cartridges. These Cartridges come in a 2 pack and are made to fit most undergravel filters. They work with any lift tube of the following measurements: 11/16 inches // 27/32 inches // 15/16 inches // 1 1/8 inches. Furthermore they serve as replacements for when it is time to cycle out aquarium filter media.