Madam's Woman cave also known as he Orchid greenhouse needs these as the outside temperature range from 40 degrees F to 100 degrees F on the same day. They work perfectly opening and closing the vents as needed.

I placed this unit in my greenhouse on a side window to create better cross ventilation. I already have two of the same vent openers that operate the ridge vents on the greenhouse and they have been working flawlessly for the last years. I will admit to trying to save a buck and previously installing a "lesser brand" of opener on the side window. It did not make it a year before failing.

I went back to the tried and true and am happy I did so.

I very much recommend this vent opener.

Works very well in my homemade greenhouse. The closing springs are very strong.