This is the Auto-i BSD1000 Blind Spot Detection Kit. It comes equipped with two sensors which are mounted on the rear sides of the vehicle facing outwards, where they detect cars, bicycles, or any other object that may be in your blind spot.
The kit also comes equipped with 2 LED indicators which are mounted near your side view mirrors to provide visual indication of an object in your blind spot.
Lastly, there is a speaker that also comes with the kit which emits an audible tone when you are attempting to make a turn or change lanes (when your turn signals are activated) and there is an object detected in your blind spot.
The BSD1000 can provide a huge increase in lane changing safety and really is a must for any vehicle.