The Hagen A1420 filter pad is designed to fit the following:
The Fluval A1420 Filter Pad for Fluval Chi - 3-Pack is a three pack of filter pads for 5 and 6.6 gallon Fluval Chi Aquariums. This Chi filter pad provides both chemical and mechanical filtration to remove odors, debris and other contaminants from your tank. This aquarium filter pad arrives custom-sized to easily fit inside of your filter chamber and prevent debris bypass.
Fluval A1420 Filter Pad for Fluval Chi - 3-Pack specifications: