The SEGRE N31000 is a comfortable and durable N99 mask, with adjustable nose clip and straps for a superior fit. The SEGRE N31000 sits in the highest classification for a mask: N99 (NIOSH approved). In order to achieve this classification, tests are performed on the mask to measure it's filtering efficiency of minimum 99% and the maximum level of inward leakage. All SEGRE masks are NIOSH marked, and conform to personal protection equipment regulation.