Certified as a Master Bladesmith by the American Bladesmith Society, Bob Kramer is one of the only Master Bladesmiths in the world specializing in kitchen cutlery. Although he is most widely recognized for his blades, Bob is also an expert on sharpening. In that spirit, he has collaborated with Zwilling to create the Kramer by Zwilling sharpening and cleaning collection. This cleaning stone, returns your stones to a pristine like-new condition with a quick and easy polish. Hand wash.