3-Stone Hone Fits Cylinders 27/32" to 2" (21.4-50.8mm). Controlled pressure makes it possible to polish or hone with just one stone grit. Square ends of stones hone to the end in step-cut and blind-end cylinders. 240 grit stones are 1 1/8" long. Flexible driver. * Larger the grit number, the finer the stone. * 180 is medium grit *Stones are interchangeable *Stones are 3/16" wide *10050 replacement stone set (gray) *O-ring is part #10120