The mercury facemask is constructed of polypropylene fiber. Polypropylene is a superior water repelling fiber that won’t accept water. It is also very strong and has the lightest specific gravity of any man-made fiber. It is a perfect facemask for when you are working hard and need to stay dry and warm. It is also supported by wigwam and its 110+ year history and reputation as a quality USA family owned business that stands behind their products. This item is made in the USA and carries the wigwam 2-year guarantee. Visit www.wigwam.com for more details