5-1/2" x 4-1/4" x 3/16" flexible foam sponge that is coated on one side with Aluminum Oxide abrasive. Ideal for sanding in hard to reach places. Used by professional painters, drywall sanders and furniture refinishers. Can be used on wood, metal and painted surfaces. Great for general polishing in the woodworking, cabinetry and automotive industries. Medium is equivalent to a 120-150 grit in traditional sandpaper, Fine is equivalent to a 220-280 grit in traditional sandpaper, Very Fine is equivalent to a 320-400 grit in traditional sandpaper, Super Fine is equivalent to a 400-600 grit in traditional sandpaper. 5 sponges per grit, 20 sponges per pack.