The Rion Automatic Roof Vent Opener helps to keep your greenhouse at the right temperature throughout the day and all night long. Crafted from durable metal, this roof vent opener automatically opens and closes the vent as the temperature changes to keep your greenhouse at the correct temperature. Designed to gradually open and close the vent, this system allow for the right amount of air flow for cooling. Solar powered and heat activated, this opener features a metal cylinder containing a mineral which expands when heated and shrinks when cooled, effectively controlling the opening and closing of the window. Designed for use with all Rion Greenhouses.