The reversing alarm is an indispensable element in dangerous working environments. The high-frequency alarm can actively prevent accidents. It gives commercial vehicles additional safety when manoeuvring and reversing. In some countries, the installation of a reversing alarm is mandatory for motor vehicles with limited rear visibility. The vehicle must have an audible reversing alarm that is louder than the ambient noise. A sound level of more than 90 dB is often prescribed. Structure and function: The reversing alarm emits a warning tone as soon as reverse gear is engaged. In this way, it warns other road users of the backing vehicle. Warning alarms are available in different volumes depending on the application. For example, reversing alarms with a signal volume of approx. 90 dB are used in urban traffic and warning alarms with a volume of more than 100 dB are used on construction sites with very high ambient noise. A reversing alarm that is 3 dB louder than another one already has twice the volume.