Palram Automatic Vent Opener was designed to automatically control the temperature and humidity levels and provide additional ventilation when needed, making gardening easier. As the air inside the greenhouse warms, the vent gradually opens to allow the correct amount of air flow into the greenhouse and closes when the temperature cools. The vent arm was designed with a metal cylinder containing wax which expands when heated to push a piston, which raises the window, as the air gets warmer, then contracts as it cools, closing with the use of a spring and resetting the piston. All you need to do is to install it on your roof vent window and it automatically starts working. The Automatic Vent Opener operates without the use of electricity and is compatible with all Palram greenhouse models only. • Opens roof vent automatically as temperature warms for air circulation and heat relief, closes when temperature cools • Mechanic system, solar powered - start opening point: 12°-15°C • Easy to install • Suitable for all Palram greenhouses