Features Include: Medium Grit (280) Diamond Surface (Uninterrupted Diamond Coating), Brass Threaded Insert for Stainless Steel Thumb Screw, Ergonomic Plastic Housing, Made in the USA! Designed for use with the Lansky Controlled Angle Sharpening System. Diamond Coatings are the most abrasive type of sharpener; they're ideal for modern, wear resistant tool steels. The medium 280 grit diamond hone is perfect for maintaining and sharpening a slightly dull edge.