Give your cat the key This door reads your cats unique 15-digit microchip ID and only allows access to the programmed pet; programmable collar keys are sold separately for cats without microchipsSelective Entry for Your Cat Give your cat (and up to 39 other programmed pets) exclusive freedom to come and go while restricting the entry of unwanted animals (like those clever foxes)Lock when you need to The manual 4-way lock allows you to control your cats access, allowing you to lock it at night to keep your kitty safe inside; set to Locked, Unlocked, Enter Only or Exit OnlyProtect your home from the elements The energy-efficient weather stripping and 2 magnetic locking points increase insulation and stop drafts from creeping indoors