The Media Pads are a 2 stage activated carbon infused fine mesh that filters out impurities and keeps your water crystal clear. Compatible with the Aquatic Filtration Kit. The workhorse of the filter system these should be replaced about once every four to six weeks to keep the aquarium clean and the filtration working at its peak performance. Features: --Carbon Infused --Each pad lasts up to 4-6 Weeks --4 pack The Media Pads are a 2 stage activated carbon infused fine mesh that filters out impurities and keeps your water crystal clear. Compatible with the Aquatic Filtration Kit. The workhorse of the filter system these should be replaced about once every four to six weeks to keep the aquarium clean and the filtration working at its peak performance. Carbon Infused Each pad lasts up to 4-6 Weeks 4 pack