Penn-Plax Cartridges FC4-Fits Undertow and Perfect-a-Flow...

Penn-Plax presents the Filt-a-Carb Replacement Activated Carbon Media Cartridges. These Cartridges come in a 2 pack and are made to fit the lift tubes Undertow and Perfecto Perfect-A-Flow filters serving as a replacement for when it is time to cycle out aquarium filter media.