Needed liner for inside of cat flap to avoid cat scratching itself on brickwork, this extension fulfilled all needs, easy to fit and my cat has no problems using the flap now
I bought a regular size cat flap and the extension I was sent was woefully short , I knew it would not be long enough to act as a ' roof ' as this was stated in the description, but it was at least 6 inches (150mm) to short to go around the edges and the bottom. There was enough material but not in the right dimensions.
This extender is great, easy to cut that fits in very deep walls like conservatory walls . It does involve a little bit of modification/ Work than the more expensive extender parts.. I added a cardboard roof with water proof tape on it/ super glued it to the cat-flap fascia . But all worked out well.