Free flow of air without too much wind is essential especially during the growing season. Halls Automatic Vent Opener uses temperature sensitive cylinders that expand and contract to automatically open and close your greenhouse roof vents. Provides ideal growing conditions, even when no one is home!
Easy to install, the opener simply replaces an existing vent arm. Ideal for hinged vents weighing less than 15 lbs. May be adjusted for different opening temperatures. No batteries or electricity required. One-year warranty.
This item is NOT recommended for use with ALL Halls Cold Frames — the aluminum frames are not wide enough for a secure attachment.