3M 2135 P3R Particulate Filters. Stand alone, lightweight particulate Filters, Lightweight, Low breathing resistance, 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: 20xWELand#160;(Half Mask) or 40xWEL (full face mask), Standard: EN143and#160;, Approval: CE marked, Workplace Exposure Limit 1 Box 20 Filters (NOT PAIRS).