I go back and forth between NW Ohio and NE Indiana all year long to our lake home and back. Tons of deer any time of year. I put those deer whistles on my SUV and haven't hit any deer. Of course I haven't hit any elephants either.

They say that the whistles are quite effective. Any opinions on them one way or another?

I saw a write up from a woman who manages a fleet of vehicles and she said it greatly reduced their deer/vehicle contacts by installing the whistles.