Best Seller | Canopia Prestige Grand Hobby Gardener & EcoGrow Automatic Roof Vent Opener | 2 H x 2.7 W x 15.7 D in | Wayfair 702107 The Automatic Vent Opener was designed to automatically control the temperature in all Canopia Greenhouses. As the air inside the greenhouse warms, the vent gradually opens to allow the correct amount of air flow into the greenhouse and closes when the... more | | $79.99 $74.30 FREE shipping go to store |