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

After my car was hit by a deer, a friend told me about this product. I decided to give it a try. I only used one (they recommend two) because the car needed repairs and I knew the front grille would be replaced, but I still had an overnight drive ahead of me. As far as I know it only worked when I was driving on a dual carriageway and swerved the car in front of me to avoid a small dog. As I drove by, the dog had already left the lane and ran away from my car, but kept looking at my car. Who knows if he heard the whistle or not, but the car in front of me didn't honk and neither did I. I just found it odd that the dog was looking back and attributed it to the whistle. Now that the car is fixed I've installed both whistles.