The extra-extra coarse (120x) is for rapid material removal. The extra coarse (220x) and coarse (325x) are good for initial lapping of uneven chisel or plane blade faces and fixing nicks. The fine (600x) is for finer lapping or general sharpening. The extra fine (1200x) is for fine sharpening of tools, cutlery or carbide. The extra-extra fine (8000x) produces a mirror finish.