They are pre-assembled, have no spare parts and require little or no maintenance. Their lightweight, well-balanced design helps provide greater worker comfort. Low profile design allows for a wider field of vision and greater comfort while wearing glasses or goggles. A re-sealable storage bag helps keep respirator clean between uses. The 5000 series respirators are available in three sizes to fit a wide variety of facial sizes. All respirators/filter assemblies can be used up to the NIOSH approval limits, 10 times the permissible exposure limit, or the maximum use concentration allowable in applicable OSHA standards, whichever is lower. EA