Fre-Cut abrasive papers have a special non-stearated "no load" coating that helps shed sanding residue for better efficiency, and also helps prevent "fisheyes" (cratering) in waterbase finishes. Fre-Cut sandpapers last longer that's why we use them in our own workshops.
See details below
These papers are graded on the "P-scale," indicating a truly uniform cutting surface (read about abrasive grading scales in our Finishing Step-by-Step book).
Here's how we use these abrasives in our own instrument shops: "After spraying the build coats on my guitar finishes, I sand with 320 girt Fre-Cut, then spray and sand again. Then I move on to 400, 600, and 800 grit. Don't skip grits! Using all the grits makes the work easier for each sheet, and they last a lot longer." Todd Sams, StewMac Production Manager and builder of Sams guitars