Doberman Security Portable Door Alarm with Flash Light, 1 alarms ULTRA PORTABLE &amp; LIGHTWEIGHT - Completely portable, easily to install/remove - use at home OR while traveling SPRING CLIP TRIGGER - alarm triggered with unauthorized entry POWERFUL 100DB ALARM - Alerts you of any intrusion and break in, loud enough to alert neighbors EASY INSTALLATION - Simply hang the unit over the doorknob and place the metal clip between the door and the doorjamb - no tools required Includes 2 Button Cell Batteries