Features Made of quality material, and convenient to use. This products need to be refrigerated before use it. Perfect for your greenhouse window. NON ELECTRIC: No batteries or electricity required, uses solar energy, open or close the greenhouse vents as temperature rises or drops AUTOMATICALLY: Simply opens and closes your greenhouse window as the temperature changes automatically, maintains the best growing temperature and prevents your greenhouse from overheating. CONVENIENT: With the automatic window openers, you can be sure of an even temperature in your greenhouse day and night. They allow thermostatic ventilation control through the roof windows of your greenhouse. Product DescriptionYosoo Automatic Greenhouse Window Opener Greenhouse Window Roof Vent Opener