BAC sells individual sheets of 3M Wet or Dry 9"x11" sandpaper to keep on hand in your hangar- no need to buy the entire pack.  Available from 80 up to 600 grit.  Used for Clear Coat Blending, Featheredging, Fine Feather Edge, Paint Defect Removal, Paint Finishing, Paint Preparation, Primer Sanding, Rust Finishing.