Mine is the Hella Dual Tone kit with the two horns and I think it's about 11 years old at this point.
It's good for highway traffic where when you hit the horn, it's probably to ward off somebody who doesn't see you. In the city, if you're reminding somebody that a traffic light is green, it's enough just to give the horn a little tap.
One thing to look out for with this dual tone kit and probably Hella's tri-tone kit, also:
-Electrical connections to the pump itself. Hella provided latchless blade-type connectors on mine. If your air pump is mounted upside down and the connectors are crimped, the connection can get disturbed (probably due to gravity, driving on trails and rough roads).
This happens and no horn when you need it. I had this horn installed, then I moved, so I ended up correcting this myself.