[Save Your Car] A pair of whistles sends out wind and ultrasonic signals at speeds over 35 mph in a collaborative environment, which will guide them effectively and prevent any further damage to your car. These will work above 35 mph. [Easy to install and remove] The bottom of the whistle is a super glue strip, which can be installed on the front bumper or roof of a well-ventilated vehicle. It won't fall off even when driving when it's raining or snowing. You can also tighten the base with two small screws. They can be removed from the base for cleaning or car washing. [Safety Gift for Drivers] That's a defensive auto accessory for drivers living in the wild. The whistle produces ultrasonic frequency and wind warnings to reduce vehicle collisions. Buy this warning device for your loved ones - anyone you may come across [Reminder] Please check and clean the pneumatic whistle regularly to make sure the hole is not blocked/clogged by debris. You should check the whistle from time to time to make sure that it is still mounted on the vehicle and that there is no blockage in the hole.