I don't know about the grits, but I've seen the medium listed as 15 micron, fine 6 micron, and UF at 3 micron on spydercoforum and various grit charts. Here's one such chart stickied in the maintenance, tinkering & embellishment section of the main forum https://www.bladeforums.com/threads/the-grand-unified-grit-chart.856708/