Gray - Ultra fine. For light finishing. Excellent for sanding before/between finish coats. Non-ferrous metals. WoodNon-woven synthetic fiber impregnated with abrasive grain for surface conditioning without damage to or removal of base material. Resists loading and heat build-up. Wet/dry construction for use in a wide range of applications. Available in a variety of grades from heavy duty to polishing applications. Reusable and long lasting design for economical use