Fixing method for the scanner coil - a cable tie attached to the ceiling of the wall tunnel. I wanted to ensure that whatever fixing method was used it did not require any (permanent) modification to any part of the catflap as not only could this potentially prohibit fitment elsewhere at a later date (e.g. into a door in the conventional fashion) but it could also invalidate the warranty. A non-ferrous fixing was also desired so as not to interfere with the operation of the scanner coil.