A microchip flap opens only for registered animals, which stops entry outright — the remaining gap is tailgating, where a confident cat follows yours through on the same swing.
Selective entry works. Here is what it does not cover.
What it stops
Any animal whose chip or tag is not registered. Up to 40 pets can be programmed on some models, 25 on others.
Tailgating
A cat waiting outside can follow yours through before the flap closes. No flap prevents this entirely.
What reduces it
A curfew that keeps your cat in overnight — fewer swings, fewer opportunities. Feeding indoors so there is nothing worth entering for. And locking the flap for two weeks if an intruder has already learned it, so the habit fades.
If it continues
Some models control exit as well as entry, which changes the pattern of when the flap opens at all.
This does not replace your device’s manual. Blade temperatures, locking mechanisms and cleaning procedures differ from model to model, and the manufacturer’s instructions take precedence over anything written here. Unplug a device before dismantling it, check a hot blade or an air nozzle against your own hand before it goes anywhere near an animal, and keep a mechanism that closes or rotates under supervision until you know how it behaves.
Last reviewed 2026-08-17