The Marina i110 /i160 Replacement Power Cartridge is made specifically to fit inside the Marina i110 and i160 internal filters. The outside of the power cartridge features polyester foam to trap fine particles; while the inside chambers contain carbon to remove pollutants and odors; and zeolite to eliminate toxic ammonia for a cleaner, healthier aquarium environment and crystal clear water. Note: For best results replace every 4 weeks. For model i160: do not replace both cartridges at the same time in order to ensure constant presence of beneficial bacteria. Key Features: 2-pack. Provides mechanical, biological, and chemical filtration. Polyester foam traps fine debris; carbon removes pollutants and odors; and zeolite eliminates toxic ammonia. Easy to replace. Designed to fit the Marina i110 and i160 Internal Filters (A301, A306).