Sandpaper coarseness is determined by the size of grit on the paper—ranging from extra-coarse to extra-fine. Using sandpaper that's too coarse could damage the material you're working with.

If you play 10-15 hours per week, expect to notice spin reduction after 3-4 months—even with ... texture or exceeding USAP’s grit limits. Fine Sandpaper (320-400 grit) – Lightly rough ...