This high-tech security alarm transforms an ordinary doorknob into a highly sensitive burglar alarm. In order to gain easy access to your home, burglars will first try your doors to see if they are unlocked. If a burglar touches your outside doorknob this device will instantly emit a loud alarm to scare him away and alert you to the attempted entry. Unlike other alarms, the burglar will be stopped before he enters your home. Even if he is wearing gloves, the alarm will sound as soon as the outside door knob is touched. No installation required: simply hang on the inside doorknob of any wooden door. Please note that this alarm will only work on wooden doors.<.u> As an additional deterrent, an alarm warning decal is included. Requires one 9 volt battery (not included).