Bought as a replacement for our previous Staywell 21 Catflap (20 year old!) Chose because no mains or batteries required and hoped it would fit in the existing wall opening, which it did with only minor adjustment.
Was concerned about the strength of the magnet on the cats collar, visions of cat bringing in pieces of metal; none yet :)
Took cat 2 attempts to get used to the new flap, after that she has been going in and out every hour like its a new toy! We did rub it all over with her blanket don't know if it helped.
One small improvement proposal; it would be useful to have a setting where no collar needed, might help timid cats get used to it. (small piece of tape over the latch works)
Overall, what do I know, the cat likes it!!