Diamond coated 4mm round section steel hones for sharpening small blades such as captive ring cutters, bead cutters, small ring tools and hook tools. The coated portion of the blade is 55mm long by 4mm diameter. It has a flat one side and a small vee groove on the other. Fine grit,
The handle holds the blade with a 1/4 inch collet so the handle can be detached and used to grip other things. It has a pen clip so it can stow in your pocket.
Works on tungsten carbide. Can be used wet or dry.