Tom Activated Carbon Pad for Rapids Pro Series PS3 & PS4 - 2 Pack 

This carbon impregnated material filters and purifies the water. Removing harmful waste material, polishing and eliminating odors as aquarium water filters down through this media. The high-grade activated carbon effectively removes discoloration and harmful chemicals while the carbon pad traps large particulate matter and other wastes as they enter the filter. Activated Carbon Pad 2 Pack.