Pack of Three, save $20. MedPure Surgical and Medical Masks is a Level 3 mask with high filtration capacity while retaining low breathing resistance to ensure the mask can be tolerated for extended periods. There is no known resistance to PurePurge™, a key mask constituent, which has been clinically proven to kill Coronavirus, Enveloped and Non-Enveloped Viruses, Gram Positive and Gram Negative Bacteria.