The Hagen A1384 is the correct replacement insert for the following filters:
The Hagen A1384 Activated Carbon Filter Insert -3 Pack is a set of replacement filter inserts for the Aquaclear 50 and 200 Power Filters. This three pack of aquarium filter inserts is manufactured with activated carbon to absorb odors, discoloration, and impurities within water. The Aquaclear A-1384 is for 20 to 50 gallon aquarium sizes and is of research grade quality.
Hagen A1384 Activated Carbon Filter Insert -3 Pack specifications: