Marineland's Emperor Power Filter Cartridge is designed to meet the absolute highest standards. Each pre-assembled cartridge slides easily into place, providing superior mechanical and chemical filtration. The cartridge mechanically filters water through a double thick poly-fiber pad. Debris and waste particles are trapped, and water is chemically filtered through the Black Diamond Premium Activated Carbon. Inside the cartridge, a patented ribbed backing ensures even distribution of activated carbon to deliver maximum water-to-carbon contact. The result is crystal clear, crystal clean water.