Advance silicone material for increased comfort and greater durability Proprietary 3M CoolFlow valve helps makes breathing easier Dual-mode head harness adjusts easily for either standard or drop-down mode Exhalation valve cover directs exhaled breath and moisture downward to reduce fogging Color-coded to indicate size (small, medium or large) for easy identification This half facepiece reusable respirator 7500 Series uses advanced silicone material to help provide comfortable and durable respiratory protection. The 3M Cool Flow Valve helps make breathing easier and can reduces heat and moisture build-up for cool, dry comfort.