UK Cambridge Mask Face Pro N99 Washable Reusable With Valve Deactivator (Assorted Styles)Note: The XS size does not come with a valve and a head strap. This is designed for toddlers or very small children. Available in XS S, M, L and XL sizes. Product Description The Cambridge Mask PRO meets the N99 (one step up from N95) standard and is built to filter out 99. 6% of particles, bacteria viruses in the air. Cambridge Maskfilters out pollution particles such as PM10, PM2. 5 and PM0. 3 as well as bacteria and viruses using a unique triple