Transforms an ordinary doorknob into a highly sensitive burglar alarm. In order to gain easy access to your home, burglars will first try your door to see if it is unlocked. The Pro-Tech Door Alarm utilizes dual-sensing technology to enable it to protect both metal & wooden doors. For most doors (wooden doors with metal knobs), the touch sensor will detect a person touching the outside doorknob and will instantly emit a loud 110 dB alarm to scare him away and alert you to the attempted entry. Even if he is wearing gloves, the Pro-Tec-Door Alarm will sound as soon as the outside doorknob is touched. For metal doors or those with wooden or plastic doorknobs, the vibration sensor will detect the attempted forced entry. You can use the chime mode at home to notify you of visitors or in a business to announce customers. FEATURES Protects your door from unwanted entry Simply hang on the inside doorknob Chime or 110 dB Alarm Even works if the burglar is wearing gloves Touch and Vibration Sensors Scares away a burglar before they enter Great for home and travel REQUIRES 3 AAA batteries