At 70 x 25mm; these mini whetstones are small and easy to carry. Excellent for router bits and turning tools. FineDMT uses micronized monocrystalline diamonds bonded to a substrate in giving a consistent grit size and coverage across the stone, this process ensures a long lasting performance. Rather than going up in numbers for the finer stones, they refer to the size of the diamonds in Microns.Fine – Restores to a fine edge any knife or tool that is slightly dull. For woodworking, this step is done before micro beveling and polishing.Colour code: Red. Diamond size: 25 micron (600 mesh).