The Ruby Sharpening stone is Light, portable, and Anti-frictionIt's extremely hard, maintain their shape well and are resistant to wearInstall easy in the a tool or machine, also easy sharpening and polishing all kinds of exact knivesFor sharpening and polishing chilled steel, alloy steel and precision parts etcSharpening stone can use oil or waterStone size: 15 x 2 x 0.5cmGrit: 3000Color:rubyQuantity: 5 pcsMaterial: Ruby WhetstonePackage Includes:5 x Ruby Sharpening Polishing Whetstone OilstoneOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.