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

I've been using them for several years, unfortunately I didn't replace them before the trip, my husband doubts that they work. We are traveling in an area that is very populated by deer. We hit one, I hope not seriously, when he ran away. From now on I always test them before I ride and I've never had a problem so I think they work. My only issue right now is that I have a Hyundai Santa Fe and they are too big to fit in the grille. Are there others that fit these vehicles?