Description: -Solar heat sensing greenhouse automatic window spring opener. -Made of superior stainless steel, heavy-duty, Maximum opening Load: 7 kg / 15 kg -Working Principle: As the temperature changes automatically, thermal expansion and contraction, the black cylinder maintains the best growing temperature and prevents your greenhouse from overheating. -Solar powered, automatic open or close the greenhouse vents as temperature rises or drops. -Enery-saving and eco-friendly, no eletricity needed. Specification: Material: Superior Stainless Steel Size: Approx. 38x10x5cm / 14.96x3.94x1.97inch Maximum window opening: 45 cm Maximum opening: 30 ° depending on adjustment and load -Single Spring Kit: Max. opening weight load: 7 kg Adjustable open temperature range: 20 ° -25 ° / 68 -77F -Double Spring Kit: Max opening weight load: 15 kg Adjustable open temperature range: 15 ° -25 ° / 60 -77F Package Includes: 1 Piece Greenhouse Window Opener Note: Please do not use the opener where the temperature will exceed 50 ° (122F). Please do not remove the cylinder, the opener cannot be stopped by manual.