Penn-Plax Filtrx Purifying Media for Canister Filters - Compatible with Cascade, Marlin, and Other Aquarium Filter Systems with Trays - Activated Carbon (CFSCB1)
Penn-Plax Filtrx Purifying Media for Canister Filters – Compatible with Cascade, Marlin, and Other Aquarium Filter Systems with Trays –Zeolite for Ammonia Removal (CFSCB2)