8" Diamond Hand Files Set - Square, Flat, Round, Half-Round for Metal, Wood & Jewelry Crafting | Professional Grade USA-Made Tools for DIY & Industrial Use

Must use water (can use oil but water won't plug up like oil can). Don't use on softer metals, they're best for high carbon, hardened alloys, tungsten carbide and stuff like that. Awesome for drill bits! But you will need water to keep diamond from plugging up. Good for mower blades as well. Love my diamond files!