Gardening Naturally Automatic Louvre Vent Window Opener

https://www.gardening-naturally.com/l... Give your greenhouse the ventilation it needs with our automatic louvre vent opener. It uses the power of the sun to automatically open and close based on the tempreture you set. It works by using a wax cylinder with expands in the heat. Comes complete with step by step instructions. Fit's most standard greenhouse louvre vents. Opens windows from 17-25 degrees celcius. Made from aluminium zinc coated steel.