Each preassembled rite-size and emperor cartridge has a patented ribbed back that evenly distributes carbon for maximum to c. No by pass, no tea bag effect, no messy assembly required. Changes in an instant. Larger Polyfiber Filter Pad. Our Heavy Duty Emperor Filter Cartridge Delivers Two Full Ounces Of Activated Carbon Filtration And 45% More Mechanical Filter Area. B/1 PACK