Fällkniven Flipstone sharpening stone, FS4

The Flipstone sharpening stone is an automatically folding sharpening stone that can be used on two sides. The dimensions could be compared to the ones of a pocket knife. The FS4 is just slightly bigger than the FS3. You can therefore always carry this sharpening stone with you. The yellow side is a diamond sharpening stone with a grit size of 25 microns. Repairing the cut is done with this side while the maximum sharpness is determined with the ceramic side of the sharpening stone. Both sharpening stones are glued together and will not come loose.