I was using the Deer Alert unit which costs about $60.00, found this unit for under $15.00 so I thought I would try one on a new vehicle purchase. After more than 6 months of use I feel that the chirping sound of this unit works better than the steady sound of the deer alert. I have seen fewer deer using this and have seen deer a half mile away staring toward the car. I now have installed these on all my vehicles. Nothing can guarantee you won't hit a deer but for the cost of this unit why not install it.