2. Even if the size measurement is accurate, it is difficult to ensure that there is no error, because the automation of this kind of products is low, and some small errors are allowed in the production process, so it is possible that after installing a new door leaf, the gap between the original anti-theft door fan and the door frame is large, and it is difficult to ensure a good anti-theft function. Of course, if you don't mind the gap, it's ok.
3. Warranty is a problem. If the same manufacturer promises a perfect warranty, don't worry, but if the frame and the fan are different manufacturers, I don't think you will get a satisfactory promise.