2SAND's 100-pack of blue sanding discs have a plastic film backing that lasts longer than standard paper backing. The plastic film backing is more level than paper. The electrostatic manufacturing results in a more uniform scratch pattern when sanding. These durable discs fit standard 2 inch mandrels and provide great for power sanding wood bowls on a lathe or refinishing Lexan headlights. The hook and loop backing is perfect for easy and quick attachment to the sanding mandrel. The aluminum oxide abrasive is great for wet or dry sanding. In addition to single-grit packs, the assortment pack contains 25 each of 80 grit, 120 grit, 180 grit, and 220 grit.