Standard files are manufactured using top quality "standard" grade sandpaper. They are washable and disinfectable. They can be immersed in (or saturated with) 70-90% isopropyl or ethyl alcohol for 5 minutes.
Premium files are manufactured using the finest "premium" grade abrasive paper, sourced from around the world to produce the highest quality and longest lasting nail file. They too are washable and disinfectable as the Standard files but may also be immersed in an EPA-Registered disinfectant for 10 minutes.
Zebra "standard" files are non-washable and non-immersable! Zebra "premium" files are washable and immersable for up to 10 minutes.
Click on this link for Proper Disinfection of Cushioned Abrasive Files, Buffers and Blocks instructions.