Credit card size diamond hones for sharpening all kinds of blades. British made from stainless steel - lasts longer than cheap imported ones. Double sided steel, medium grit one side and fine grit on the other. 82mm x 50mm area of diamonds on each side.
Ideal for HSS turning tools of all kinds. Works on tungsten carbide (router cutters etc) as well. Can be used wet or dry. Fits conveniently in top pocket.