ABS Anti-Collision Ultrasonic Deer Repeller - Car Siren for Wild Animal Alert The deer whistle operates effectively at a range of 1/4 mile and requires the vehicle to travel at least 35 mph to function.It emits a loud sound carried by airflow, designed to attract the attention of nearby animals and alert them to the approaching vehicle.Constructed from ABS plastic with a matte finish, the whistle is and stable under various weather conditions, long-term use.Its compact size measures 3.6 x 1.3 cm (1.42 x 0.51 in), making it suitable for mounting on the front bumper or any flat of the vehicle.This device emits an audible through the air, intended to warn deer, elk, moose, antelope, kangaroos, and other wildlife near the road, helping to prevent collisions between vehicles and animals.The whistle is compatible with most vehicles including SUVs, trucks, motorcycles, and ATVs.The package includes 2 pieces of deer whistles.