This is a replacement cylinder for automatic window opener. Highly sensitive, automatically reacts to weather changes, so you don't have to stay near the greenhouse. No electricity, uses solar energy, opens or closes the greenhouse vents when the temperature rises or falls. The automatic skylight opener for greenhouse windows is suitable for most greenhouses to open or close the window automatically. Saves time and labor, can also provide a better temperature for plant growth. Specifications: Condition: 100% new Temperature range: 20~25 ℃ / 68~77 ℉ Size: approx. 33 * 1.5 cm / 12.99 * 0.59 inches Color: black + silver Material: stainless steel + plastic Package contents: 2 * Window opener Only the above package content, other items are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3 cm.