This is a battery operated cat door that unlocks (going inside) by reading the cat’s microchip. Our cat was chipped at our shelter for around $10, but commercial vets are also able to do it for a bit more. No need to worry about lost collar keys, or magnets. Keeps out unprogrammed animals. The door also has the standard four-setting mechanical overide locking feature of: in-out, in only, out only, locked. If your cat is not chipped, you can also use an RFID collar key (not included).
We previously had a magnetically keyed cat door, but you then have the choice of using a safety collar and losing the (not cheap) key every now and then, or using a non-safety collar and risking the cat strangling itself.
Raccoons eventually defeated our magnetically keyed door. They haven’t defeated this one (yet), although the mechanical parts of the latching action are similar.