If I am reading correctly, you might just want an regular cat flap door? As in not radio transmitter type? If so, I use these on the door between my laundry room and the enclosed patio. They have a magnetic device inside that holds the door closed until the kitty pushes on it and the magnet is really just to keep the door from flapping, it does not *lock* anything. I bought ours at Petsmart and believe it cost around $25 and it has been in place for the past ten years or so with no problems. The five cats use it many times each day. It needs cleaning off now and then and the screws need to be tightened once in awhile to keep it secure in the door. I have the smallest one and our big Dylan (20 pounds) has to do a bit of squeezing but it does not stop him This size might keep Vallis from using it?? It *does* have a lock on it which is just a plastic switch that you can slide to allow the door to open only one way or to keep it closed. That part does not work very well because the cats can still force their way and jiggle the switch to open. So, if you are wanting the thing to stay closed. it might well wear out. There was another model that was held on with sticky tape but I doubt that would have held up nearly as well - mine is actually screwed into the door.

Good luck!!