Broan 355SOBR Surface Mount Solar Powered Attic Ventilator, Brown 7-1/2-Inch high profile flush mount design for attics up to 1600 square feet and hurricane rated to 140 mph winds 20 -Watt solar panel circuitry captures sunlight even on overcast days and totally weatherproof panels designed for optimum efficiency constructed of tempered glass to resist hail and extreme weather conditions Whisper-quiet - direct current - variable voltage - sealed ball bearing and hardened shaft motor with steel motor housing dynamically balanced for superior performance Specially designed one piece - 12-Inch aluminum 5 blade fan pitched for maximum air flow and operates quietly with no harmonic noise Heavy gauge, stainless steel bird and rodent screen with 1/8-Inch openings provides maximum protection from insects and animals without impeding air flow