The G60 Sanding Sheets are ideal for wood You can select the sanding sheet based on your requirement and usages It is classified based on usage sanding sheets are classified into extra fine (320) for primer, sealer and between coats sanding, very fine (220) for very fine sanding of bare surfaces, primer and sealer sanding, Fine (180/150) for finish sanding and cleaning of bare surfaces, Medium (120/100) for light removal and smoothing of bare surfaces, Coarse (80/60) for moderate removal and leveling of surface imperfections, Coarse (40) for heavy removal, stripping and dimensioning Velcro 8 hole