HIGH QUALITY: The core technology is the hydraulic cylinder containing a high-quality plant-based wax replacement cylinder for automatic greenhouse window openers or aotovents as they are commonly called. UNIVERSAL: The replacement cylinder is compatible with most greenhouse window openers with single or double springs. SOLAR POWERED: This specially designed cylinder, containing this wax, acts as a thermostat for window opening in greenhouses; there is therefore no need for a power supply. Uses solar energy to heat the cylinder. Open or close the greenhouse vents when the temperature rises or falls, helping to maintain optimal growing conditions in your greenhouse. REPLACEMENT CYLINDER ONLY: A replacement cylinder for greenhouse window openers. The complete set of automatic vent opener is not included. EASY INSTALLATION: Easy DIY installation without obstacles Number of parts delivered: 1 Size: approximately 33.5 cm long