1.Suitable for 12V air horn, compatible with car/truck/vehicle trumpet/air horn. 2.Voltage: 12V voltage, diameter: about 50mm, height: about 110mm. 3.Red surface performance is stable, easy to install, match your car horn! 4.Brand new product with high quality, waterproof and sealed, can work in fresh water or salt water environment, suitable for almost all weather conditions. 5.The price is reasonable and the product offers good value for money, enough for daily use.