How exactly do they work and are they worth it?
We currently don't have a flap - the good old fashioned opening the door works with us as I like to make sure my two are in at night. I hate them being out. But I've recently been thinking of getting a flap.
The problem is that I live in cat neighbourhood where every other house has a cat. If I bought a standard flap it would mean my house would be a free for all as they're all little cheeky furries. I often find one of the neighbours cats stretched out in my garden.
There's also the resident Tom who goes to everybody's house and eats each cat's food so he's a cert to come through.
I know you can get the collar flap ones but neither of mine have a collar. Winter-boy had a nasty reaction to one so I've never tried him with one again. And I haven't bothered with winter-girl having one in case she suffers the same reaction.