3M 2091 P100 HEPA Particulate Filters protect from the smallest of particles. They are extremely lightweight and flexible and snap right onto any 3m 6000 series half masks which provide excellent comfort while working. HEPA filters remove 99.9% of particles .3 microns or bigger. 3m 2091 filters protect you from toxic dusts, asbestos, lead, welding burnt metal particles, and many more environmental particles and allergens. The apply to a 3m 6000 series half mask by placing the back of the filter into the mask and turning to snap lock in place. The 3m 2091 particulate filters are sold in pairs.