Help prevent dangerous animal collisions with the RoadPro Deer Warning Whistle 2-Pack – a simple yet effective ultrasonic animal alert system designed to reduce the risk of roadside wildlife accidents. As your vehicle travels at speeds of 35 MPH or higher, each whistle emits a high-frequency sound wave that warns most animals of your approaching vehicle, giving them time to move away from the road. The ultrasonic signal is inaudible to passengers and pets inside the vehicle, ensuring a comfortable ride while keeping wildlife safe. The low-profile design attaches easily to the exterior of your car, truck, SUV, or motorcycle using the included self-adhesive mount, with no tools or wiring required. Whether you are driving through rural highways wooded areas or regions known for wildlife crossings the RoadPro Deer Whistle provides an extra layer of protection for both your vehicle and the animals that share the road. Black.