Lightweight and breathable, this top-quality filtering material is perfect for face masks. Non-woven spun-bond polypropylene 1.25 ounce per square yard (on par with most surgical masks) and 20 inches wide. We recommend using this filter material in conjunction with tightly-woven quilting cottons for a stylish design and good quality filtration. Machine Wash and Tumble Dry. Do NOT use iron directly on the mask filter material. If you must iron your project, be sure to use a low heat setting and a pressing sheet or other heat barrier.