This Parking Sensor System helps you to get rid of those costly collisions that happen inevitably. Once installed, It will automatically turns on when reversing and parking. For the display unit with built-in buzzer, Parking Sensor System gives forth audible beeps if an object is detected while backing up. And audible alarm sound frequency will increase as the distance getting shorter with Bi-Bi sound, it helps us get far away from danger and damage when parking! I believe that this Parking Sensor System would be your superb choice!