Upgrade your attic ventilation system with this powerful and energy-efficient ventilator fan kit from Air Vent. It was used for less than 100 hours and works like new. It has a 17 inch diameter plus protruding mounting tabs, including four corner shields shown in the photos to seal off a square opening.  It includes an adjustable thermostat to automatically turn on the fan when the attic temperature exceeds an adjustable value and does not have humidity control. It is made of durable plastic and steel materials and has four blades that can efficiently ventilate and cool your attic. The fan weighs 11 lbs and draws 3.7 Amps with 110 VAC. Perfect for a pre-summer ventilation system upgrade, this attic gable vent kit is a must-have if you want to keep your house cool when it gets hot in the summer.