Medtex M5 Fabric MaskSize: M, standard size, same as surgical masks, disposable. Proven to filter 95% of 5 micron particles even without a filter. Easy to breathe with a 3 layer muslin fabric structure, a unique feature of Medtex. Reduces dirt accumulation with a 3 pleat downward design. Center lock sewing technique for the strap and binding helps prevent the ear loops from moving, and the drawstring on the cheek allows for a snug fit. It fits various face shapes, even