It could be between 800 and 2,000 grit, and in this case the guys use 1,500-grit discs to dry sand the texture of the paint. Wet sanding discs could also be used.

The next step is back to wet sanding with 3M's 3,000-grit Trizact foam discs. They spend more time with this one as many as 20-25 passes.