The Univent allows solar-powered control of top and side mounted window vents thanks to its dual springs. Univent window openers have an adjustable opening temperature of 60° F to 75° F and an 18" maximum opening which would be reached at approximately 20° to 30°F above opening temperature. Univents are made from corrosion resistant materials including aluminum and stainless steel. This model is recommended for use with Grow More and Solar Harvest greenhouse vents because they include a mounting bracket made for these greenhouses. A minimum of 1 opener is needed per roof vent. 2 openers are recommended for each Grow More roof vent in very windy areas (50 mph winds or higher).