Manufactured exclusively for Hagen's Fluval FX4， FX5 and FX6 Filtration Systems， these foam blocks perform mechanical filtration， the crucial first stage in the filtration process. These foam filter pads capture large particles and are custom fit to prevent bypass. They enhance biological filtration， and are ideal for freshwater and marine aquariums. For use with Fluval FX5 and FX6 External Canister Filters.

• Captures large particles
• Custom fit to prevent bypass
• For freshwater and marine environments
• Bulk packaged to save you money and save our environment from wasted packaging
• Fits the FX4， FX5 and FX6 Canister Filters