The SG-250 Original Grindstone differs from conventional grindstones in more ways than one. The unique composition of the stone, together with the SP-650 Stone Grader, gives you a wide range of sharpening characteristics in a single stone. The stone grader adjusts the surface of the grindstone from 220 grit, to a surface as fine as the equivalent of 1000 grit. This is a great advantage, because you can do the fine sharpening using the same jig setting as when you first shaped the tool.
The SG-250 Original Grindstone fits the Tormek T-8, Tormek T-7 and earlier Tormek models with a grinding wheel 250 mm (9.84") in diameter and 50 mm (1.97") wide. It's also available for the Tormek T-4 Original and Tormek T-4 Bushcraft, but with different dimensions as the SG-200 Original Grindstone.