An excellent introduction to the benefits of diamond sharpening. Available in three grades, coarse, fine and extra fine, these 70 x 25mm handy stones can be used to sharpen a myriad of small items but, be warned, if you purchase one of these to try out the system then it will not be long before other items follow! We can guarantee that's how impressive it is! Coarse 325 grit = 45 micron, Fine 600 grit = 25 micron and Extra Fine 1,200 grit = 9 micron.