Sanding Block Swop Block Sheet MEDIUM, UK 220 approx. tungsten carbide grit. The interchangeable Steel sheet folds around the end of the block, the punched holes enable a quick release and secure fit. SHEET Size 170 x 70mm. Block size when the sheet is fitted 120 x 70mm. A very popular roughing out block, popular with Stone Masons. FINE approx. equivalent UK 420 grit sandpaper COARSE approx. equivalent UK 180 grit sandpaper EXTRA, EXTRA COARSE approx equivalent UK 80 / US 24