Optional Automatic louvre vent now available at extra cost (shown in main photo). Fits to left-hand side of frame. New louvre vent for value range growhouses and lean to models. Fits to L/H side of frame. The most useful accessory you can buy for your Value Mini greenhouse or Growhouse. Designed to automatically open as the temperature rises above 65 degrees Fahrenheit (18 degrees C) and then close again as the temperature cools. The unit is ideal if you are out for the day and the weather changes. It is also very useful for models that catch the early sun, as sunrise can be 5:30am in the Summer. Grease filled opener requires no electricity to operate.THESE CAN BE FITTED RETROSPECTIVELY – you will need to drill a 4mm hole in the endplate of your existing frame.