SAVING LIVES AND PROPERTY: two pair of whistles deer warning devices is friendly for animals. Deer warning can emit ultrasonic automatically day or night at speeds above 35 MPH and will warn deer up to 1/4 mile away. The purpose of the deer whistles is to stop the deer from running in front of your vehicle. UPDATE SELF-ADHESION TAPE: We upgraded the normal double-back sticky tape to adhesive tape which is pretty sturdy, they will stay in place even through a professional car wash. And each whistle comes with an additional adhesive pad for replacement. DEER WARNING DEVICE: Made of premium plastic which can resist all weather, even stay at outside extreme heat or below freezing, the device can work well. QUICK& EASY INSTALL AND REMOVE: Just peel off the tape cover and stick the device to your bumper or grille. And the whistles can conveniently be removed from base for wash your car. Two deer warning whistles are recommended per vehicle. Product description This set of whistle contains four ultrasonic whistles and four wind whistles. Usually, one ultrasonic whistle(a whistle with hole in the tail) is matched with one wind whistle(a closed-hole whistle), which is the best effect. Compatible:For The deer whistle wildlife warning devices compatible with all Cars, SUV, Truck, Motorcycle and ATV. colour:Black Material:ABS size:5*3.5*2cm Package Contents: 4* open whistle 4* close whistle Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.