The Sure Flap adapter is used when installing the SureFlap Microchip Cat Door
or Pet Door on a thin surface such as a sheet aluminum panel
Sure Flap also recommends using it for wall installations as it makes attaching the frames to the inside and outside of the wall easier.
This adapter can be used to install the pet door in glass. This does not work for doors, which have tempered glass, as tempered glass cannot be cut.