I admit that I was very surprised that this actually works. Every day I go out expecting it not to work but it still does.

I have used these exact openers for years, they have never failed. The only thing I can say is if you have cold frames, buy them. You will never regret the purchase!

I've used it in my shed converted to a greenhouse for a few months. Starts opening at about 72 degrees and totally opens around 85 or so. It's the second one I bought, the first one was a cheaper brand and this one is a better quality all around for just a few more dollars. All I need now is an auto-fan that will come on at the same time but I'm sure that won't be as easy to find.

I was quite pleasantly surprised by how well they work. I just had to make some minor adjustments to my greenhouse window frame but, it does save me time repeatedly going out to manually adjust the windows.

It works as it should. I didn't realize that I could turn the piece to adjust the temperature range that it will open and close the vents which is great because I grow different plants throughout the year. This was the easiest part of automating my greenhouse this year and has already worked as a Fail-Safe when we lost power and my other systems couldn't operate. My vents still opened and I didn't lose a single seedling.

We have a small, inexpensive greenhouse. The daytime highs ran 120 - 130 degrees F when the outside temperatures were in the upper 70's to lower 80's. Going out to raise & lower the vents twice a day, every day was not attractive to me. This auto vent was easily adapted to our greenhouse and functions perfectly. Very easy installation for a moderate DIY person.

I used this for a mini-greenhouse planter that I purpose-built so I was not replacing a window opener from another manufacturer. It has worked flawlessly since I installed it.

This is a great help to our greenhouse. When we are working we are comforted to know these will open up if it gets too hot. I love them!

I bought 2 for my HF greenhouse vents and they open and close at good temps. I like that they open gradually the hotter it gets, and close gradually as it cools down.

I am extremely pleased with how well these open our greenhouse windows. Our windows are 2' x 5' double pane metal/wood frame windows that we have attached to hinge out and up. These openers have no trouble opening and closing the windows. I only purchased one to make sure it was going to work and once we installed it and saw how well it worked I ordered 3 more for our other windows.