Equip your vehicle's onboard air installation with the premium Kleinn FIT89 complete plumbing and fitting kit, engineered as a direct-fit component package for the HK8 and HK9 ProBlaster train horn systems or for universal high-pressure custom configurations. Built for maximum pneumatic reliability, this comprehensive hardware kit includes a complete set of heavy-duty 1/4-inch NPT brass fittings to guarantee a completely leak-free setup under extreme pressure. To streamline your airline routing and ensure safe operation, the high-performance kit comes fully loaded with a part number 2151 145 PSI automatic pressure switch, a part number 52175 175 PSI safety relief valve, a part number 52835 air tank drain valve, a part number 50040 hex plug, and a 51212 straight compression fitting. Designed for a clean, professional finish right out of the box, this ultimate upgrade package also includes a part number 318-BK black momentary horn push-button switch alongside a vial of Kleinn's exclusive Juice-1 liquid thread sealant, giving you everything needed to successfully complete or service your air horn system.