Fine: The best utility sandpaper. Fine grades smooth scratches left by coarser grades and rough up painted surfaces before accepting new paint.
They're also good for sanding drywall. When you just need some for hand-sanding, or to use with an orbital sander, this is the grade you'll most likely use.
Available in 2 colors and different grit
3M Black - 100 , 150
Reddish brown - 100, 60 , 36