Dual Function: Can be used as a door stop alarm and door stopper, Its rubberized bottom prevents the door sliding and alert off intruders. Door stop alarms are available for door-to-floor clearances of 0.6'' and 1.2''. | 3 Level of Sensitivities: High-Medium-Low Sensitivities, which can be adjusted according to your own needs. | Loud Alarm: Very loud shrill that would definitely scare someone away with 120db alarm. Weight: 4.5 oz. | Powered by 9V Battery: The door stop alarm powered by 9V battery, One piece can be used for a year under normal circumstances. Very practical. (Note: Battery not include) | Easy to Use: No installation required, Simply place the alarm behind any inner pull door (home, hotel, etc). very convenient to take with you when travel or stay indoor alone. A really must have around you.