Key Features: 1. The open-hole whistle makes a loud whistle in the wind, helping to attract the animal's attention and alert the deer. 2. Easy to install and disassemble. 3. It can also be simply removed when you are not using it. 4. The range is 1/4 mile and only works when the car is traveling at least 35 mph. 5. Our deer warning devices are friendly to deer and other animals. 6. Compatible with all cars, vehicles, SUVs, trucks, ATVs, motorcycles. 7. Save animals and increase your driving safety while reducing vehicle collisions. Specification: Material: ABS. Size: 6 x 2.5 x 4 cm/ 2.3 x 0.98 x 1.57 inches. Package Includes: 4 x Car Deer Whistles, 1 x Instruction Book, 8 x Red Tapes.