Viking Horns VIK-12 Train Air Horn Installation Kit for On-Board Air Systems With Heavy Duty 1/2" Inline Electric Air Valve and Air Hose Includes a 1/2" heavy duty inline electric air valve solenoid With 1/2" high pressure air hose for greater air flow that will produce a louder horn sound Includes: air pressure switch, air gauge, connecting brass fittings, horn button, Ideal for new train horn installations, or upgrading your current air system to an 1/2" air system Air horn kit is recommended for use with 3 gallon air tanks or larger