Sanding Block HOLDER for Swop Block Sheets. HOLDER Size 120 x 70mm. Black plastic holder with felt pad, wing nut fasten. The interchangeable Steel sheets, range from Fine to XX Coarse. The sheets fold around the end of the block, the punched holes enable a quick release and secure fit. SHEET Size 170 x 70mm. A very popular roughing out block, popular with Stone Masons. FINE approx. equivalent UK 400 grit sandpaper COARSE approx. equivalent UK 180 grit sandpaper EXTRA, EXTRA COARSE approx equivalent UK 80 / US 24