I brought the back cover for the cat feeder, it completely prevents cats from going up the back. it doesn't prevent if you have a determined cat push in the side of the entrance and the allowed cat doesn't leave and lets them eat then there's nothing that can stop that. I did see something on amazon reviews about an intruder mode which closes the bowl if another microchipped cat pushes in but none of my other cats are microchipped so I cant say how that works or if its even a thing.

Absolutely A Must To Have For The SureFeed Feeder. Purchased This To Keep Stray Cats From Sneaking Through The Back To Get To My Semi-Feral’s Cat Food. Works Perfectly & An Added Bonus, Shelters The Feeder From Flies & Cat Urine. Made From Durable Plastic & Super Easy To Attach. Great Price….The Rear Cover Is Good Quality & Sets The SureFeed Feeder Up Nicely. Pet Direct Wrapped & Boxed With Great Care & Courier/Delivered Fast. Thanks Pet Direct For A Great Service….5 Stars Overall. Love My New Feeder/Rear Cover & So Does My New Friend Midnight…