Micro chip operated cat flaps, any good?

[HazelBite]

So we've been having visitors who are eating all the cat food, my two are "grazers" and are also complete wusses and just stare at the "burglers".
So we are thinking along the lines of one of those cat flaps that is sensitive only to your own cats micro chips.
Does anyone have any experience of them are they effective?

Yes, highly recommend Sureflap

Make sure it is 2-way on the chip. Ours has a chip activated catch on the inside only. Local Tom has learnt to bash door inwards against catch, then drag it outwards as it bounced back, as nothing to stop it opening outwards!

Yes, we love ours and it has kept unwanted visitors at bay. You can also set it so if they come in then they can't go out again, useful for vet days!