Offering fantastic working Comfort, the 3M 4255+ half-face respirator mask features an enhanced low-resistance valve and a lightweight, well-balanced design to make it easy to wear. It's also ready to use and maintenance-free, and like other respirators from the 3M 4000 Series, it incorporates a central position for the exhalation valve to help reduce build-up of heat and moisture to keep you cool, calm and collected.