12V/24V (it works for both) Light Duty Reversing alarm / Beeper with Night Silent FacilitySplash Proof Case, Minimum 85 dB at 1m.Night silent facility, which deactivates the unit when the vehicle lights are turned on.Black wire: Negative (-12V) / GroundRed Wire: Positive (+12V)Yellow Wire: +12V from Headlights - Power on yellow wire will disable the alarm.DO NOT connect yellow wire if you want the reversing alarm to function regardless of headlights being turned on/off.
eBay