Each preassembled Rite-Size Cartridge filters water through a double thick polyfiber pad which traps more dirt and debris, faster. The cartridge is packed with super-efficient pure Magnum Activated Carbon--it keeps working longer after most carbons stop. It's better than a bag! Just shake and rinse. The patented ribbed backing evenly distributes carbon for maximum water-to-carbon contact. No bypass, no "tea bag" effect--just crystal clear, crystal clean water.