These Cat-Mate Electronic Pet Doors are operated by one 9 volt battery (not included) so they don't require a location near a wall outlet. The doors sense the collar key, which is a small magnet, and unlocks. The cat then pushes through. The pet doors are 'self-framing'. Two collar keys are included with each pet door.

A '4-way' lock rotary dial is visible in the lower right hand corner of the 08AM254. Cat Mate has recently both enhanced the performance of the  small electronic and lowered the price! This has been a very reliable performer over the years.

The 08AM256 uses the smaller collar key used by the 08AM254 and is suitable for cats. The Dog Mate Electronic Small Dog is exactly the same pet door but uses a larger, and slightly more expensive, collar key better suited to smaller dogs. Both key types will unlock both doors.

The 08AM256 doors use sliding tabs to accomplish the 4-way lock rather than a rotary dial (they're two red tabs and one green in the center. Unfortunately, the cat is hiding them).

You'll find spare collar keys and other parts at the 'Keys & Flaps' link above.

You might suppose that one way to use the Cat Mate pet doors to keep one pet in while allowing another out would be to reverse the pet door so that it controlled pets on the inside but not, obviously then, on the outside. That idea works provided that you carefully shield the now outside portion of the pet door from the weather.

Note:  Reversed installation (turning the pet door around so that it controls from the inside rather than from the outside) will void the warranty.

Another idea that we have encountered is installing two pet doors--one at each end of a fabricated wooden tunnel made long enough that the flaps don't interfere with each other. Then the outside unit controls access from the outside and the inside unit controls access from the inside. Such an installation would be easiest to accomplish in a wall.

Cat Mate Electronic Large Cat Flap

CAT MATE