Designed for hand sanding, each 9” x 11” sheet can be cut to the size of your sanding block. During Stage 3 of the 3M Body Repair System, use 320 grit sandpaper to shape and sand glaze or spot putty prior to priming. After sanding with 320 grit sandpaper, apply primer per manufacturers recommendations. Then, use 320 grit sandpaper during Stage 4 to sand primer. Follow this step by sanding primer with 400 grit sandpaper to refine 320 grit scratches. 320 grit sandpaper used to shape and sand glaze or spot putty prior to priming Also used to sand primer Contains 5 sheets of 9" x 11" sandpaper Use during Stage 3 and 4 of the 3M Body Repair System Can be used with PN03148 or PN03149 3M Sanding Block