We use woven cotton sheeting in our protective masks. The straps are made of a knitted elastic material. Our masks meet all CDC requirements for protective face covering, as they have advised that wearing a mask is more protective than going without a mask.
For our Sustainable KN95 mask, it is made of 50% hot air cotton, 30% non-woven polypropylene, and 20% meltblown propylene. This creates a 5-layer, lab-tested filtration system.