The SureFlap Cat Flap Installation Adapter is ideal for installing the SureFlap Microchip Cat Flap or the SureFlap DualScan Microchip Cat Flap in glass, masonry, or certain types of doors. It covers the gaps that remain between the device and the edge of the circular hole when installed in glass. This allows for the installation of the flap in holes ranging from 212 mm to 260 mm in diameter. The package includes two discs, one for the inside and one for the outside of the glass pane, door, or wall.