CPR CS50 SIPHON AQUARIUM OVERFLOW BOX by CPR Aquatic. **** Overflow Box Selection Chart **** **** PRODUCT MANUAL **** A 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 to easily change the level in your tank. * Black top reduces algae growth. * Plastic screen to prevent fish loss. * Quiet operation. CS50 Specifications: * Flow Rate: 300gph * Outflow Size: 3/4" Bulkhead * Width: 6" * Dimensions: A: 6.5", B: 7.5", C: 1.5", D:1.25", E: 3 7/8" , F: 4.75", G: 7.25", H: 5.5", I: 3.5", J: 2.75", K: 3"