I give it three stars because the fault may be mine. I installed it on a window with old glass that was initially supported by small nails (wooden windows) and then a window stopper was placed. The instructions say that it will take a week for the stopper to tighten completely. In my case, with temperatures at 30 to 32 degrees, it took 10 days and the stopper had not tightened. I had to remove it from 3 windows... and use foam stoppers that did the job quickly and perfectly.
However, I repeat, it may not be the product's fault but mine.