Spyderco Tri-Angle Stone - Ultra Fine Made of highest quality material Manufacturer: Spyderco Spyderco Tri-Angle stone - Ultra fine Ultra-Fine ceramic triangular rods for the Spyderco Sharpmaker sharpening system Designed for professional-grade finishing and polishing of sharpened edges for maximum sharpness Sharpen all types of edges including serrated edges Sold individually Made in USA