EasyPro SSS35 Vianti Falls Stainless Steel Waterfall Spillway, 35.5-Inch Wide, 2-Inch Lip Rated for 1800 gallons per hour of flow, and has 2-Inch Lip Internal baffle calms incoming water for a smooth even flow over waterfall Dual 1-inch female threaded inlets in back wall At the recommended flow rate, the water should not drop more than 4 feet from the spillway's edge to the reservoir's top. If the spillway is higher than 4 feet, then the water sheet will break apart. The spillway is made to be placed about 12 to 48 inches above the basin. (Basin not included.)