The 3M 6099 Filters protect against organic vapours (boiling point above 65?C, inorganic vapours, acid gases, ammonia and its derivatives, mercury, formaldehyde up to 10ppm and particulates Filters are specially designed and shaped to give "swept-back" position to enable excellent field of vision and balance. Lightweight, Low breathing resistance, Well balanced when fitted to a mask, Provides excellent field of vision as a result of the unique trapezoidal shape, Bayonet fitting system ensures precise and secure locking Standard: EN14387 Approval: CE marked Maximum use concentration when used with full face masks: 20xWEL for organic vapours, inorganic, acid gases and ammonia; particulates up to 40xWEL - Only for full face masks, For use with Full face Masks Only, 1 BOX = 4 FILTERS (NOT PAIRS)