Aluminum oxide coating (320-400 Grit) Wet/dry sanding Washable for longer use Box of 20 Norton 4-1/2" x 5-1/2" Fine (320-400 Grit) Soft Touch Sanding Sponges feature a flexible foam back that contours to the shape of surfaces for an even scratch pattern. They are made with aluminum oxide abrasive and are ideal for smoothing surfaces before an application of paint, primer or sealer. Turners love them, especially when turning pens, bottle stoppers, or even larger, more intricate turnings.