Grit #3000 Rectangle Ruby Knife Sharpening Grindstone Whetstone Polishing Stone Oil Stone Features: brand new and high quality. The Ruby Sharpening stone is made from sintered crystals of synthetic ruby. It's extremely hard, maintain their shape well and are resistant to wear. Because they are so hard they can sharpen and finish extremely hard metals such as carbide gravers, but also work on non-metal like glass, porcelain and quartz. For sharpening and polishing chilled steel,alloy steel and precision parts etc. These Ruby Sharpening stones can sharpening and polishing for triangle sawtooth, circular saw blade, plane blade edge, small serrated mould. Sharpening stone can use oil or water. Specifications: Color: red Size: 150mm/5.91"20mm/0.79"5mm/0.20 Grit: 3000# Note: Transition: 1cm=10mm=0.39inch Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package Includes: 1 Sharpening Grindstone