Magnetic, collar-controlled cat doors may be right for you if you live in a rural area with a lot of wildlife, or an area with a big population of feral cats. Automatic cat doors won't allow any animal access to your home without a collar key or collar transmitter to activate the cat door.
However...magnetic cat doors will open for any pet that wants to exit the home. If you need two-way control please see the PetSafe Electronic SmartDoor.
TIP: If you have pets that vary greatly in size, for example a huge Mastiff and a small cat, the cat would have trouble pushing through a flap that has to be big enough for a Mastiff. A motorized electronic pet door is the solution for you because there is no flap to push. Motorized pet doors slide up and down to open and close, similar to a garage door, and can be used by any size pet no matter how small or large.