85% of full power in winds over 120 mph. Most wind generators lose up to 90% of their output in high winds. This new 3-bladed design only loses 15%! It also sets a new standard for quiet operation. Light weight cast aluminum and stainless steel components combine ease of installation with durability -- only weighs 20 lbs. Built-in "smart" voltage regulator stops voltage surges and battery overcharge. 60" rotor diameter, 550 watts.