Excellent Features of Reverse Sensor System: 1. Very relible and interference-resistant ECU 2,The latest generation of sensors featur very wide horizontal detection ngle and excellent vertical angle. 3, The diagnostic mode can indicate exactly which one of the sensor is defective, if any. 4,The system can automatically memorize, then neglect the tow-br, bumper bar or spare tyre. This model consists of: 1) 1 ECU (electronic control unit) with 1.2m power cable; 2)2 or 4 sensors with 2.5m cable; 3) Accessory: user's manual, 1 drill bit for every 40 ultrasonic sensors. according to order quantity. Technical data: 1) Working voltage: 10.5-16V; 2) Max. power: 5W; 3) Max. audible alarm distance: 1.7m; 4) Audible alarm volume: mute, 70dB and 90dB (at 1m) adjustable; 5) Working temperature: -40 +75°C Packing details: 20pcs/ctnN.W.: 15kg G.W.: 16kg Measurement: 50x37x33cm