This is a replacement cylinder for automatic window opener. High sensitivity, automatically responds to weather changes, allowing you to keep your greenhouse managed without constant supervision. Non-electric design uses solar energy to open or close greenhouse vents as temperature rises or falls. Greenhouse window automatic roof vent opener is suitable for most greenhouses to open or close windows automatically. Saves time and labor while helping maintain better temperature conditions for plant growth. Specifications: Condition: Temperature Range: 20~25°C / 68~77°F Size: 33 * 1.5cm / 12.99 * 0.59in Color: Black + Silver Material: Stainless Steel + Plastic Package Contents: 2 x Window Opener Note: Only the above package content is included; other products are not included. Lighting and different displays may cause slight color variations between the item and the image. Measurement allows an error of +/- 1-3cm.