Simple self installation, please watch the video in the images and read the product description below for a simple to follow guide on your replacement greenhouse window opener. If your greenhouse automatic window opener has stopped working, simply replacing the cylinder will restore it to normal operation, no need to replace the whole vent opener. Compare with your existing opener, if the piston looks and measures the same, then it’s the same. Check the dimensions image in the pictures for full details. Begins to open around 16°C to fully open at around 26°C, helping to maintain optimal growing conditions in your greenhouse. Screwing the piston in or out can make small changes top opening. Replacement piston only, universal and compatible with the majority of greenhouse automatic vent opener, both single and double spring automatic window opener and louvre vents.