Saving Wild Lives Property: two pairs of whistles deer warning devices is friendly to animals, emit ultrasonic automatically day or night at speeds above 35 MPH, then deer gonna run away, by which to stop the deer from running in front of your vehicles. Waterproof Self-adhesive Pad: pretty sturdy, and will stay in place, each whistle comes with an additional adhesive pad for replacement. Quick Easy to Install and Remove: Just peel off the tape cover and stick the device to your bumper or grille, and the whistles can be removed the base easily, 2 deer warning whistles are recommended per vehicle. Great Compatibility: compatible with all cars, such as motorcycle, truck, SUV, ATV, and so on. Safe Gift for Driver: The whistle produce ultrasonic frequencies and wind sound warn, which help to reduce vehicle collision effectively. High quality deer warning device: made of quality plastic that work with all weather conditions. Please check and clean air-activated whistles periodically to ensure that the holes do not become. blocked/clogged with debris. Material: Plastic Size: 5 x 2.3 x 2cm Color: Black Quantity: 4