Halls Automatic Vent Opener

Free flow of air without too much wind is essential especially during the growing season. This Automatic Vent Opener uses temperature sensitive cylinders that expand and contract to automatically open and close your Halls greenhouse 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.

Note: Not recommended for use with Halls Cold Frames -- they do not have a large enough frame to attach the opener.