[Protect your vehicle ] A pair of whistles emit wind and ultrasonic signals in a collaborative environment at up to 35 mph speed, which will effectively steer away the , prevent any further damage to your car lost. hese will work above 35 mph. [ Easy to Install and Removable ] The bottom of the whistle is the strong adhesive strips , allow to mount on the front bumper or roof of a vehicle which with good airflow. It would not fall off even driving when raining or snowing. You can also screwthe bases down with two small screws. they can be removed from their base for cleaning or going through car washes. [ Safe Gift for Driver ] That is a defensive car accessories for driver who live in a wild area. The whistle produce ultrasonic frequencies and wind sound warn, thereby reducing -vehicle collisions. Buy this warning device for your loved ones - anyonewho could encounter a or a few quantity of delivery: 2 piece (Package contents: Only the above package contents, excluding other products.) size: 5*2.3*2cm (Reminder: The size is measured manually, please allow 1-2 cm measurement error) color: black colors (Due to different monitors and lighting effects, the actual color of the item may be slightly different from the color shown on the picture.) JINYI