Very happy with this solenoid. Responds quickly to a short blast of the whistle and easily replaces my factory horn. I believe it lets some air through the piston in the solenoid for a few hours so you can lose pressure in the tank overnight if you don't have an extra valve to control your solenoids, but I don't mind. Ordered a second one for the other side! Maybe I'll put my factory horns on my mower.