The Automatic Vent Opener was designed to automatically control the temperature in all Palram - Canopia Greenhouses, and the Sun Room Six and Sun Room Eight. As the air inside the greenhouse warms, the vent gradually opens to allow the correct amount of airflow into the greenhouse and closes when the optimal temperature is reached. The vent arm was designed with the use of natural wax that expands as the air gets warmer, to push a piston which raises the window, then contracts as it cools, closing with the use of a spring. The Automatic Vent Opener operates without the use of electricity. Assembled dimension: 11" W x 2" D x 2" H Automatically control ventilation Protect your plants from heat exposure Provides gradual airflow - opens more the hotter it gets. You can adjust the temperature that the opener begins to activate over approximately a 5-degree range. Easy to install Works with Palram - Canopia Prestige, Grand Gardener, Eco Grow, and Hobby Gardener greenhouses Works with Palram - Canopia Sun Room Six and Sun Room Eight lean to sunrooms Heat activated, no electricity necessary, adjustable temperature range