Our filter cartridges meet the absolute highest standards of water purification performance and operational ease. Each pre-assembled cartridge slides easily into place, providing superior mechanical and chemical filtration and making replacement fast, dry, and effortless. The cartridge mechanically filters water through a pad of couble thick poly-fiber. Debris and waste particles are trapped, and water is chemically filtered through Marineland's Black Diamond Premium Activated Carbon. Inside the cartridge, a patented ribbed backing ensures the even distribution of activated carbon to deliver maximum water-to-carbon contact, resulting in crystal clear, crystal clean water.