Greenhouse Automatic Vent Opener Solar Roof Vent Opening Kits for Wooden&Aluminum Greenhouse Auto Hothouse Window Opener Agriculture Greenhouse Acessories Lifts 15.4 Lbs(7kg)

I installed this on the roof vent of a Palram 8 x 10 greenhouse. it’s like magic. Opens and closes with the temperature.This would have been a 5-star review if the directions had been better. All was good until Step 7: Screw the cylinder into the housing until the thread is equal length on both sides. I screwed and screwed and screwed until my arms were tired and I could screw no more. No movement. At all. I took a break and then went back to the greenhouse determined to get it done. This time, instead of screwing, i pushed the cylinder in hard and it went right to the threads. From there, I screwed it in until the threads were equal on both sides. And PRESTO! It worked! Don’t be afraid to force it in the beginning. Hope this helps someone avoid my frustration!