Air horn installation kit for 1/4" on-board air systems. Ideal for new train horn installations, or replacement of old worn out parts on your air horn system. Kit contains 120/150 psi air pressure switch, 0-To-240 psi air gauge, universal horn button (switch), brass fittings, air pressure safety release valve, Teflon tape sealer, 1/4" electric air valve solenoid, and 1/4" air hose.