The emperors feature not one pump (as in ordinary power filters), but two separate water pumps. The flow and filtration efficiencies are unmatched by other filters in their class. Contains: Two Rite-Size E Filter Cartridges, Two 4 Oz Refillable Media Containers, Two Spray Bar Driven Bio-Wheels, Certified Flow: 400 Gph Size/Quantity: 400 GPH