The Red side is suitable for sharpening all woodworking tools, carbide tooling, router bits, 3D bits, woodworking and kitchen knives.
The Blue side is suitable for sharpening general carpentry tools, tin snips, wood flat bits, Stanley knives, masonry drills, chisels, garden tools, fish hooks, darts etc.

Blue: Coarse 325g, 45 micron
Red: Fine 600g, 25 micron