Fasten the Black Key for Infra Red Dog Door to your pet cat or dog and enable your pet to move indoors and outdoors at will. No more waking up in the middle of the night to let Fido out for a potty break. As your pet approaches the automated pet door, the key sends a signal that opens the door for them. This system is great for preventing unwanted guest in your house such as the neighbors pet dog or the neighborhood raccoon family.