Stellar s advanced At Ease back up sensor send ultrasonic waves into the space behind your vehicle when you reversing, Stellar s revolutionary tri sensor system will automatically warn you against any obstructions that you may run into by emitting a sequence of pulse tones, The closer and louder the tones get indicates the distance of the object from your car, Detailed instructions insures easy installation even for the weekend mechanic, Backed by a limited lifetime warranty, SKU: DSD446150