This is a replacement cylinder for an automatic window opener. Highly sensitive, 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 the temperature rises or falls. Ideal for most greenhouses, this automatic roof vent opener helps open or close windows automatically. Saves time and labor while promoting better temperature conditions for plant growth. Specifications: Condition: 100% New Temperature Range: 20~25°C / 68~77°F Size: 33 x 1.5cm / 12.99 x 0.59in Color: Black + Silver Material: Stainless Steel + Plastic Package Contents: 2 x Window Opener Note: Light and different display settings may cause slight color variations between the image and the actual item. Measurement allows an error of +/- 1-3cm.