3M™ Maintenance Free Reusable Respirators 4000+ Series for effective breathing protection. These fully-assembled half masks (e.g., 4277+, 4279+, 4255+, 4251+) feature enhanced valve assembly for reduced exhalation resistance. The non-allergenic, silicone-free face seal offers a comfortable fit, and the integrated filters are maintenance-free. With a lightweight design, centrally-positioned exhalation valve, and adjustable head cradle, these respirators provide comfort in various conditions. The models offer protection against gases, vapours, and particulate hazards. Choose from four options, each including a resealable bag for hygienic storage. For use in hazardous industrial environments. Show more