Marine Boat Solar Powered Stainless Steel Ventilator II this water resistant 4" solar powered ventilation comes with intake & exhaust blades. Ventilator Cutout Diameter 4 3/4", Measuring 8 1/2" diameter and 2 4/5" H It moves up to 900 cu.ft./hr of air when powered on solar and with a slight breeze provides passive ventilation at night. Installation on flat surface. Item Number: P13025