2 PCS Deer Whistles, Auto Save Deer Whistles Avoids Collisions, Deer Whistle for Vehicles with Rubber Pads Suitable for Cars, Trucks, Motorcycles, Universal Car Accessories

I got these deer whistles for free through the Amazon Vine program. Installation was a breeze; just stick them on with the included rubber pads, and you’re good to go. Now, I can’t confirm if the deer in my area are getting the message, but so far, no run-ins with wildlife, so I guess they’re working!They’re small and discreet, so unless you’re actively pointing them out, no one will notice them. I haven’t spotted any deer doing the usual road-side shuffle, so maybe these whistles are having secret, high-frequency conversations with them after all.I didn’t pay for these, but I’d say they’re worth it if you live in an area where deer crossings are a daily concern. Four stars because while they’re easy to install and offer peace of mind, I can’t exactly ask a deer for feedback. At least they’re quiet—for humans, anyway!

These are bulkier than I expected but still subtle when installed on the vehicle. Installation was very simple and the double sided tape seems like it'll hold up. I never know if these really work but I've passed deer on the road and haven't hit one yet.