Broan-NuTone 16.75 in. x 16.75 in. Square Aluminum Aluminum Automatic Shutter Gable Louver Vent

The Broan model 433 automatic shutter is the perfect accessory to Broan gable mount powered attic ventilators, provided you have adequate air intake on the opposite side of the attic or the in the eaves. Attic ventilation is critical to making any home more comfortable while helping to lower energy costs. Stagnant air can be removed, drawing fresh air across the surfaces. The home ventilating institute recommends at least one square foot of open air inlets for each 300 CFM of ventilator capacity.