this has been the best and has solve rouge moggy entry!
I’ve never had a problem with red cats.
I fitted a magnetic one. It worked, but not 100%; a determined ginger tom managed to defeat it, I think by brute force. Any other cats with the same system would have bypassed it too, though I’ve never seen any round here.
You also need to keep an eye on collar wear; a lost collar => a locked out cat, not a huge problem overnight but not great if you’ve left an automatic feeder and gone away for four days.
Other than that it was alright, simple to fit and the locking mechanism was decent. You can allow one-way opening in either direction, or two way, or locked completely.
Catmate Elite Selective – works on RFID
You can get replacement tags, presumably?