Description These are the the passive fan exhaust shutters that keep the cold air out and warm air in while your fan isn’t running. Passive Exhaust Shutters For Snap-Fan Greenhouse Fans Specifically sized for your 20 inch Snap-Fan Corrosion resistant aluminum Protect the fan when its not running Keep warm air in when needed Passive – blown open by fan . Snap-Fan Exhaust Shutters Technical Details Shutter Installation Instructions Greenhouse Fan Exhaust Shutters by Snap-Fan
