The Kleinn Model 311 is a premium, all-brass hand-pull lanyard valve engineered specifically for roof-mount air horns to let you blast your horn with the authentic feel and control of a real big-rig commercial semi-truck. Designed for direct mechanical activation, the high-flow outlet of this rugged brass valve threads seamlessly right into the bottom inlet of roof-mounted horns, providing an instantaneous blast of high-pressure air when engaged. Built to withstand heavy-duty use and harsh cabin environments, the complete assembly comes equipped with a durable, high-strength steel pull cable and lanyard loop, making it the perfect vintage-style upgrade for trucks, classic rigs, and custom commercial-style vehicle installations.