At Marineland, we design our filter cartridges to 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 double thick poly-fiber. Debris and waste particles are trapped, and water is chemically filtered through Marineland's Black Diamond Premium Activated Carbon.?