These amazing, all-natural, high-quality stone nail files are made from quarried Arkansas stone; the same stone that professional-grade whetstones are made from. They can last a lifetime under normal use. The fastest way to spread nail fungus from nail to nail or to other people is by sharing nail files. These files can be soaked in rubbing alcohol to sterilize between uses. While using Nail Soak, you should sterilize or clean your files after each use. Each file is a different color that corresponds to the fineness of that stone; you have rough files for harder use and finer ones for finishing the filing process.