Each preassembled rite-size and emperor cartridge has a patented ribbed back that evenly distributes carbon for water to car. No bypass, no tea bag effect. Larger polyfiber filter pad traps more dirt, highest grade carbon removes pollutants. The Emperor Filter Systems, Our Heavy Duty Emperor Filter Cartridge Delivers Two Full Ounces Of Activated Carbon Filtration And 45% More Mechanical Filter Area. 2 PACK