Whenever the passenger is passing by, your digitally recorded message is played. Now your can use the power of digital recorded message to announce to customers, visitors, or passers-by. The MDP unit is a self-contained digital recorder complete with built-in motion sensor, microphone and speaker. To record your message, simply push and hold the record button while speaking into the microphone. The prerecorded message is nonvolatile, which can sustain for 10 years even power is off.