yes, i had these on my van. i do believe they work. i recently had my van in the shop to be worked on. in the meantime i drove someone elses vehicle. they did not have deer whistles. the first day i drove the vehicle, five deer crossed in front of me. if i would have had the whistles this would not happen. they just look up and stand there, they don't try to run out into the road in front of you!