80-100 extra-coarse to coarse, to shorten the nails and smooth the top layer.
100-180 coarse to medium, for preparation, casting or reduce them
180-240 medium to fine, smooth and retouch.
600-3000 extra fine, super fine to high shine finishing as granulation or polishing.
Grit is a term used in defining the coarseness or texture of abrasives;
grit is measured in numbers; a lower grit (fewer grit particles per square
inch) is more coarse.