3M 2135 P3R Particulate Filters. Stand alone, lightweight particulate filters. Low breathing resistance and a bayonet fitting system ensures precise and safe locking, Versatility: can be used on all 3M 6000, 7000 and 7500 Series Half Masks and Full Face Masks. Maximum use concentration: 20xWEL;(Half Mask) or 40xWEL (full face mask). Standard: EN143, Approval: CE marked, Workplace Exposure Limit. Pack of 20 Filters (Not Pairs).