The Seapora 300 Overflow Prefilter is a low profile acrylic overflow box that hangs on your tank and easily converts a standard aquarium into one that is reef-ready. It comes with a single foam cylinder, a nylon utube and a 1 inch bulkhead. The Seapora Overflow Prefilter supports flow rates of up to 300 GPH and is ideal for tanks up to 75 gallons.