https://imoodle.win/wiki/Insta....lling_a_upvc_Door_Pa
https://scientific-programs.sc....ience/wiki/Cat_Flap_
Professional cat flap installers will install your pet's door in either a door or a wall. The wall-mounted version is more secure, as an intruder cannot reach through. It also helps to prevent drafts and lowers your energy costs. The Tasker will mark where the cat flap is in your door, and then cut the corners. They will also smooth the edges of the frame for a smooth finish. Microchip cat flaps A microchip cat flap is a straightforward and effective