The North 7190 N99 Low Maintenance/Disposable Non-Oil Particulate Half Mask Respirator approved to the NIOSH 42CFR84 regulation. This respirator uses a patented coaxial valving system to make it the coolest, most comfortable disposable available today. With this system, rather than exhaling hot, moist air through the same medium used to inhale, the worker breathes through separate intake and outflow channels. This patented process helps avoid the uncomfortable buildup of heat and moisture common in other disposables. Fits easily under a welding helmet. Replacement filter available.