DURABLE: This diamond stone sharpening set has a large, 75cm2 surface area with 3 assorted grades: coarse, fine and extra fine, and is extremely durable. EASY TO USE: The sharpening files are ideal for quick, easy and effortless sharpening of a wide range of tools including plane irons, chisels, blades, router cutters and garden tools. NO LUBRICATION: No oil lubrication needed - they only require water.