Sandpaper Holder For 21 Inch Size Floor Buffers, 20 Inch Block, Heavy Duty Aluminum Casting Center Device With Universal Clutch Plate NP9200, Malish, 781020. Works with 21 inch sandpaper or screens. This professional grade Heavy Duty Sandpaper Driver is constructed from marine grade plywood and features a 3/8 inch thick foam pad for gripping sandpaper.