Review on Katzco Save a Deer Whistle: Ultra Sonic Noise for Deer, Non-Electric, Value 4 Pack, Avoid Deer Collisions! by Steven Latham

Bought this for my best friends parents who live permanently in a beautiful cottage in the Upper Michigan area. I go there in the summer to take a break from the hustle and bustle of city life. As I drove there, I noticed an increase in the number of deer along the roadside and in the surrounding fields. I also saw deer jumping into oncoming traffic in the middle of the road. My friend's father hit a deer a few years ago and is now paranoid about driving at night (especially at dusk). So I decided to buy him these whistles (one for his truck and one for his wife's car). He received them and installed them in both cars and so far he says he hasn't spotted a single deer. He reports that they're working pretty well so far. I will keep you informed of any changes, positive or negative.