This is a 3.5 ounce pack of Fluval C-Nodes (14023) used as the Stage 5 biological filter media in the Fluval C2 Aquarium Power Filter System (14001) and the Fluval C3 Aquarium Power Filter System (14002).
These Fluval C-Nodes for Fluval C2 & C3 Aquarium Filter Units are enriched with oxygen and used in the specially designed Fluval Biological Trickle Chamber to provide an optimum biological balance in your aquarium. They quickly reduce toxic ammonia and nitrite to help your aquatic pets thrive better.
About half of your Fluval C Nodes should be replaced approximately every 6 months - it is not recommended that you replace all of the C-Node media at one time because to do so would upset the balance of beneficial bacteria in your aquarium.
This pack of Fluval C-Node biological media is also known by Hagen part number 14023. They can be used in both freshwater and marine aquariums.