Designed with 20-gauge steel to improve security on hinged and sliding doors the Guard Dog DoorKeeper Alarm prevents forceful entry of even the largest intruders. The adjustable system allows the door bar to slide to fit most standard-sized doors and the loud 100 dB alarm will bring notice up to 1,000 feet away. Want to use it on a sliding door? Simply remove the top yolk pin and DoorKeeper is ready for action. Whether at home, school, or the office, the DoorKeeper Alarm keeps what you want out.