Gardman Greenhouse Auto Vent This very simple yet clever arm will automatically open the window as the day warms up, and close it in the evening as the day's heat fades away. You can easily adjust the vent by hand to control how warm you want the greenhouse to get before the vent opens/closes. Comes complete with fittings and instructions. This is suitable for use with any of the aluminium frame Gardman greenhouses except the 6x4 model.
