The Plain Mask is just that. It is pleated and it comes in black and white. Fits most adults. It is not a medical grade mask.
Tultex, a t-shirt company, makes them. badknees is no mask expert, but feels these are comfortable, cover the nose an mouth, comfortable around the ears, and easy to take on and off, and wear around neck when not around others.
It's a perfect mask to add to your collection. Just throw it in the wash and reuse. It's 100% cotton.