Marineland, they design their 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. Inside the cartridge, a patented ribbed backing ensures the even distribution of activated carbon to deliver maximum water-to-carbon contact. The result? Crystal clear, crystal clean water. There's a Rite-Size Cartridge for every Penguin Filter, Emperor Filter, and Millennium Power Filter. Plus, the custom Eclipse Filter Cartridge is designed specifically for horizontal placement in our extensive selection of Eclipse systems. Our color-coded packaging ensures fool-proof cartridge selection. Rite-Size B fits Penguin 150B, 110B, and 125B.