Equip your truck with the Kleinn 411 direct-fit single chrome-plated roof-mount air horn system, featuring a single premium all-metal trumpet measuring 25 inches in length with an oversized bell end to deliver the ultimate big-rig sound. Engineered for universal semi-truck and commercial vehicle applications, this massive, heavy-duty roof-mounted configuration allows you to command the road with a deep, authentic, and deafening locomotive-style blast. Designed for clean external mounting on custom or commercial rigs, this high-performance horn kit requires an onboard pressurized air system and can be operated using a manual hand-pull air valve or an electronic solenoid valve. For a proper, leak-free setup right out of the box, the installation requires a Model 330 Roof Mount Air Horn Fittings Kit, providing the ideal balance of gleaming chrome style and serious acoustic presence that serious custom truck builds count on.