Like all Marineland filters, the Marineland Rite-Size C Cartridge is designed to meet the highest standards of water purification and operational ease. These are pre-assembled mechanical and chemical filters that filter water through a pad of double-thick polyfiber and then thoroughly cleans it using Marineland’s patented Black Diamond Premium Activated Carbon. The result is crystal-clear water free of waste, debris and muckiness so you can better view your fish. It suits a wide variety of filters, including Marineland Penguin 170B, 200B, 330B, 350B as well as Aqua-Tech 20-40 and 30-60. When you order from Big Al’s Pets, you get six filter cartridges to keep your water clean and clear for several months at a time. Stock up on filters and essentials and enjoy free shipping on $75 or more.