You don’t have to worry about your greenhouse temperature or plants to wilt or damage, from extra heat or cold. You don’t have to worry for opening and closing the greenhouse vent, the Automatic roof vent opener just makes gardening easier. Automatically opens and closes the roof vent window when temperature changes. The opener has a metal cylinder containing special material which expands when heated. This pushes a piston that opens the window. As the temperature cools, the material shrinks and a spring closes the vent and resets the piston. The opening and closing of the window is gradual allowing just the right amount of air flow for cooling. All you need to do is to install it on your roof vent window and it automatically starts working. Works with ALL RION greenhouse models only.