From http://www.petsafe.net - A step-by-step guide with A step-by-step guide with installation tips, tools needed, and pet training instructions for a PetSafe Infra-Red Pet Door. Our infra-red door recognizes a tag on your cat(s) collar and unlocks the cat door when the cat is in range. After your cat has passed through, it re-locks automatically, keeping out unwanted visitors.