The sensors are BLACK in color. This device is a high-tech bionic product that uses emitted waves during operation and can measure the distance to obstacles through their reflections. The driver is warned in three ways: the digital display displays the distance to the obstacle (with accuracy in centimeters), the lit diode indicates the direction of the obstacle: L- left, M- middle, R- right and the alarm signal informs about different distances with different sounds. Maximum measuring distance 30cm-2m. Maximum current consumption 200 mA. INSTALLATION: The device may only be installed by a professional auto electrician. All connections must be insulated or otherwise prevented from moisture entering the connections. The sensors must be installed at least 50 cm from the ground and the distance between the sensors must not exceed 70 cm. Before installation, make sure that there is enough space for the sensor in this location. Hole diameter 22.5 mm. Install the main processor in the trunk of the car. Connect the power cables as follows: black wire - car ground (minus), red wire - reversing light plus wire. Install the digital display on the cars dashboard in the drivers field of vision. Install the sensors on the cars rear bumper, connect the sensors to the control unit starting with the sensor located on the left edge of the bumper in sockets a, b, c and d and to the display socket marked DISPLAY. Voltage: DC 12V Operating voltage: DC 9 - 16 V Current: 20 - 200 mA Obstacle detection distance: 0-2.5m Ultrasonic frequency: 40Khz Power cable length: approx. 80 cm Speaker cable length: 490 cm Sensor cable length: 220 cm Ambient temperature range: -30 ° C ~ + 70 ° C Number of sensors: 4 pcs Sensor hole diameter: 19 mm (hole saw included)