CPR CS90 Aquarium Overflow BoxA built-in overflow is the most efficient method of draining aquarium water to a filter. If your aquarium does not have built-in overflow, CPR Continuous Siphon Overflows/Prefilters are the best means for getting water from an aquarium to a filter system without expensive modifications to the tank. They quietly skim up to six times more water than units with tubes.The advantages of CPR Continuous Siphon Overflows/Prefilters include:Adjustable water level allows you toeasily change the level in your tank.Black top reduces algae growth.Quiet operation.CS Overflows feature a grated inlet.Specifications:Model: CS90Flow Rate: 600gphOutflow Size: 1″ BulkheadIncludes:(1) Overflow body(1) Screen and sponge(1) Vent tube with small O ring(1) Bulkhead assembly(3) Adjustment screws(1) Air line(1) Aqua Lifter pump and Acrylic Lid (included in Deluxe models)Product code: 27Item No. OF-CPR-CS90