I bought a Petporte Smart Flap Microchip Cat Flap as I had problems with numerous cats, all with magnets, gaining access to my house through my original magnetic cat flap. I thought that a cat flap that recognised my cats' chips and let only them into the house was the only answer. All went well for a while, but then I came home to a miscellaneous cats in the house again. At first I thought that they had developed a way of pulling the flap out, to permit access, but closer investigation showed that the green catch that should lock the flap was no longer moving out of the housing, so the flap was open at all times.
I telephoned Petporte customer services this morning and spoke to an exceedingly nice lady. She informed me that this was a known problem with the cat flap, due to a wire being too short, and that there was no fix at the current time. She did suggest that I stuck a picture of a cat on the clear cat flap and that might deter the unwelcome visitors! I did point out that my expensive cat flap was completely useless and she agreed. Apparently Petporte are working on a new product that should resolve this issue.
Save your money, don't waste it on this product.