I thought I would share some information that I hope is helpful. I sanded the entire bus with 320 grit using a DA sander. I bought the sandpaper at Harbor Freight, trying to save a few bucks. The last batch I got from my paint supplier here in Abilene. The cost was a little over double for the same count, 100 on a roll. They are PSA (pressure sensitive adhesive) discs. My experience was this. I should have used them from the beginning. They last over 5 times longer and don’t plug up. End result, better finish in much less time. The box shows holes in them, mine was a solid pad, therefore no holes. I guess they use the same picture on all of their sanding products.