Respirator,Face Mask, Dust Mask,Protective Mask 1.Maintenance free 2.Latex-free synthetic rubber head strap. Respirator,Face Mask, Dust Mask,Protective Mask Features1. Conforms to international standards ... for each layer, partical filtration efficiency and the shape of mask according to customer's demand in details. Respirator,Face Mask, Dust Mask,Protective Mask