SAVING LIVES & PROPERTY: Air moving through the device produces sound/ultrasound wave, gives deer advance warning, they may freeze on the roadside, rather than running across the road into the path of the vehicle. PLEASE NOTE: For better effect, an ultrasonic whistle needs match a sound whistle per vehicle. PREMIUM QUALITY & GREATER STABILITY: The set is made of quality molded ABS plastic with matte surface that endures extreme outdoor temperature. Its an upgraded version with lengthened base and 3M tape (1.97"x0.83") for greater stability. The self-adhesive tape will not damage your car paint and can be removed completely with alcohol or citrus-based gum remover etc. Each measures: 2.36" in length, 1.38" in height, 1" in width. EASY INSTALLATION: Just remove the adhesive backing and stick the whistles to the grill, front bumper, rear view mirror, or any flat place of your vehicle. Make sure the bigger ends faces the front, and the deer whistle is level with the horizon. The ideal place is where the most air flow occurs, followed by grill, front bumper. Each order comes with 8 warning device sets. Please note: Two deer warning whistles are recommended per vehicle. REMOVABLE & UNIVERSAL: These whistles can be removed from the base easily by pressing down the block button for car wash, and then installed back to the base by sliding in afterwards. Applicable for all cars, SUV's, trucks, motorcycles, ATV's and more. The range for the deer whistles is one-quarter mile and only works if the vehicle is traveling at least 35 miles per hour. Feel free to contact us if you encounter any issue, our professional customer service is standing by and committed to serve you to your satisfaction.