I would be happy if just the physical lock worked properly. I find it incredible that they sell a cat flap where the lock can be so easily forced by the cat. Admittedly Max is a bit of a bruiser, but I don't think he is that unusual a cat.

It is also very clear what is wrong with the design. The lock engages on the side of the flap rather than the bottom. The flap is too flexible. If you push on the flap hard from the inside it twists and pops over the lock, allowing the cat out and locking them out (it appears to be harder to force it back the other way).

If either the flap was more rigid, or the lock mounted centrally at the bottom of the flap (like some other brands seem to be) then the problem wouldn't happen. It seems that all of Staywell's flaps in the range have the same lock design. Our's is the magnetic one, but the manual and infra red ones have the exact same design.

It also has another couple of obvious design flaws:

The magnetic lock only operates on the incoming side, cats can leave without having a magnetic tag. This means that when the thin bit of plastic on the tag fails (or the collar comes off) and they are indoors they will be able to leave via the cat flap and get locked out.

P.S. when I was trying to find and placate Max at 2am this morning, after the flap had locked him out for four hours, I could find every cat in the area (think there were four of them sniffing around) except Max.

There is no way of disabling the magentic lock. If you realise your cat's tag has gone missing you have no way of turning off the lock to allow them to use the flap until you get a new tag.

I think I'll be taking this cat flap back, assuming I can find a better designed one.

On the plus side, the cats are now happily using the flap to go to and fro. I'm so pleased they now get to enjoy the outdoors.