Polypropylene Delta Aire HS 95 filter inserts made in USA.
Layers - Multilayers with spunbond-meltblown-meltblown-spunbond (SMMS) layers
These filter inserts do offer filtration of particulate matter and viruses up to .3 micron and utilize the same type of fabric used in medical grade N-95 masks. For use with cotton mask covers can be washed which is one of the best defense mechanisms for killing viruses. It is not recommended to wash these inserts.
DO NOT WASH FILTERS- You can mist with hydrogen peroxide and set in sun to dry for repeated use