These FFP2 NR (D) face masks are intended to protect against solid and liquid particles, according to the UNE-EN 149:2001+A1:2009 standards. They are suited to protect against low-to-average toxicity in concentrations up to 12x0EL o 10xAPF. OEL: Occupational Exposure Limit. APF: Assigned Protection Factor. (D): Dolomite clogging test for more comfortable breathing. Sold in packs of 2 or 10 units. They include adjustable bands for greater comfort and an exhalation valve.