Stainless Steel Greenhouse Automatic Spring Opening Do Windows Single Spring Load 7 Kg Ear: 12x8 cm/4.7x3 inches -Automatic opening of windows in the greenhouse with solar heat sensor -Made of the highest quality stainless steel, durable, Maximum opening load: 7 kg / 15 kg -Principle of operation: when the temperature changes automatically, the thermal expansion and contraction black cylinder maintains the best growth temperature and prevents the greenhouse from overheating -Solar powered, automatic opening or closing of greenhouse ventilation openings as temperature rises or falls -Energy saving and environmental friendliness, no electricity needed - Inner mesh panties Material: excellent stal stainless Size: Approx. 38x10x5 cm/14.96x3.94x1.97 inch Maximum window opening: 45 cm Maximum opening: 30 depending on adjustment and load -Single set of springs: Memory clock speed opening load: 7 kg Adjustable open temperature range: 20-25/68-77F -Double spring set: Maximum opening load: 15 kg Adjustable open temperature range: 15-25/60-77F The package includes: 1 piece do greenhouse opener