1/2" Air horn installation kit for on-board air systems. Ideal for new train horn installations. Also good for upgrading your current air horn system to an 1/2" system. This will give you a higher flow of air to your air horn, which will make it sound louder. Or you can use this kit for replacement of old worn out parts on your air horn system. It is RECOMMENDED TO USE A 3 GALLON AIR TANK, OR LARGER FOR THIS AIR HORN KIT. Hose end to air tank connecting fitting will require a 1/2" pipe thread port size on the air tank (if smaller size thread use a reducer. not included). This kit contains: 1/2" heavy duty electric air valve solenoid, 170/200 psi air pressure switch, 0-to-240 psi air gauge, universal horn button (switch), brass fittings, and 1/2" high pressure air hose and Teflon tape sealer.