6 total for me... I believe all the Nascar teams are running them now... I wanted them for the playback function. I can never seem to pay attention to any gauges making a run, so that function is nice for tuning/troubleshooting.
Recall function is cool, had a problem with one of my harnesses out of the box has a loose wire in the plug, did have a display issue on one of them when i first got em, I dealt directly with the manufacture and they fixed me right up, the alarm function is pretty awesome too, one of these days ill get a new wiring harness, gauge worx like 98% of the time.