Replacement cylinders compatible with Bayliss XL autovent greenhouse window openers. Please check images as this cylinder is only compatible with Bayliss XL autovent openers. Easy self installation. Please read below in 'Product Description' for a simple DIY installation guide. Opening Temp. range 16°C-26°C (60°F-78°F) helping to maintain optimal growing conditions in your greenhouse. Heat activated replacement cylinder. If your automatic opener has stopped working, replacing the cylinder will resolve the problem.