Specifically designed for the Fluval U4 filter, the U4 Poly-Carb Cartridge has two unique filtering sides that combine to provide thorough chemical filtration.

Key features:

• Chemical filter media
• Polyester side filters out fine debris and contaminants
• Carbon side filters out harmful liquid substances, colorants and odors
• Suitable for freshwater, saltwater or reptile environments
• Convenient 2 x poly/carbon cartridges