U.S. Patrol JB5322 Alarm Security Bar extends from 29 to 43

This alarm security bar with audio alert provides extra protection to secure your home, dorm, office or hotel room from intruders. 
As soon as anybody touches the doorknob, the alarm on this heavy-gauge steel bar will sound like a powerful siren or barking dog to warn you that someone is trying to enter. 
It's a simple, effective way to frighten away intruders. 
This bar extends from 29in. to 43in. to fit any door. 
Operates on one 9V battery (not included). 
30.25in.H x 3.20in.W. 
No-tool installation is a breeze.