Have a double glazed door. Not really suitable for glass door. the flap it was replacing did not need to be glued to the glass on each side, and i do not want to do this in case I need to replace flap again. It seems that the flaps on Aliexpress are all similar to this. Will look for a flap like the one that I am wishing to replace that is made to go into double glazed door and does not need to be glued to glass because it is made to connect through the existing hole in the glass.
am very happy with it!