One of the patients’ husbands handed out deer whistles for our cars to all the staff at work. He is so kind. He bought them at walmart and handed them out to the nurses, nurses aids, and therapists. He said after reaching 35 mph they would make a whistling noise that would cause deer to run and hopefully they would be gone by the time the car passed through. I followed the instructions and mounted two on my car. They really do work. It causes the deer to run before you approach. You still have to watch for that one rogue stupid deer that will run in the direction of the road and then zig zag back and forth across it, but most of them run into the woods. I will never again drive a car without deer whistles.