The idea for this product is brilliant, but unfortunatly I found this didn't work as good as I thought it might. It scanned and memorised my cats ok, but only let one of them in when in the normal mode and in all fairness to Sureflap customer support, they were very helpful in trying to put the problem right, quick on responding and sending me replacement units, ( i'm on my third now ).It seems like the problem is in the scanning area, as I watched my cats trying to get in,it seemed to work ok for the cat who "nosed" its way through the flap and as for my other cat who tended to use its paw to open the flap, it didn't work at all,he gave up trying eventually. Which makes me think that if the scanning range was slightly better over a wider area it would pick up cats who tended to stand slightly one sided to use their paw to try opening the flap and not getting in the range of the scanner. Maybe I've got an odd cat! I'm not sure but I hope that this review may help someone decide on getting one of these units or not, depending on how their cat try's to "nose or paw" their way through normal cat flaps.