Square horn is a vehicle-mounted siren designed specifically for special vehicles such as rescue engineering vehicles and fire trucks. Equipped with a 200W car horn alarm, it has clear and loud sound pressure and strong penetration, which can quickly transmit warning signals in noisy environments such as engineering sites and fire rescue. Adopting a unique square structure design with a black appearance, it fits the installation layout of special vehicles. As a wired loudspeaker, it has stable signal transmission performance, avoiding warning delays caused by wireless interference. The horn supports 12V vehicle power supply adaptation and is equipped with waterproof and dustproof structure, which can withstand harsh environments such as rain, snow and dust during rescue operations.