Bring fresh air into your greenhouse without electricity. The Solexx Louver vent keeps the rain out while circulating fresh air into the greenhouse. The rugged outdoor-grade PVC frame measures 24"W x 12"L. Three louvers made from 5mm Solexx high density polyethylene allow diffuse light into the greenhouse - even when closed! Adjust Solar Powered Opener sensitivity by turning the knob. Tighten the knob to open the vent at a lower temperature. Vent opens automatically as the greenhouse warms. Fully assembled, no batteries required.