The Alarm Slide PetSafe Ultimate by Ideal is a sliding door that can be added onto certain pet doors to alert you when the door has been opened. The Alarm Alert is simple to install and use. This pet door alarm system can be switched to on or off. When the Alarm Alert sliding door is in place and activated it will give off a warning alarm sound when the door begins to be opened. This is an excellent way to keep track of when the pet door is being used. This item is only the sliding alarm door pet doors must be purchased separately. Measures 22H x 15W x 1D inches.