Who buys this mask should know that only a mean FFP2 filter effect has (See Wikipedia under respirator):
FFP-2 total leakage at most 11%, average values is not greater than 8% protective effect at least 95%; for harmful dust, mist and smoke; Filters for solid and liquid particles; their concentration ranges against harmful substances up to 10 times the threshold limit value.
So if you have to do with fine dust has (fiberglass, carbon fiber, etc.), which should be the masks of class FFP 3 buy (there is also from 3M). If already protection, then right, FFP 3 protects better with fine particles by far:
FFP-3 total leakage than 5%, mean values not greater than 2% of at least 99%; Protection against toxic substances and against droplet aerosols, carcinogens, radioactive materials, enzymes, microorganisms (viruses, bacteria, fungi and their spores); their concentration ranges against harmful substances up to 30 times the maximum allowable concentration.
Conclusion: FFP-2 can therefore still more than twice as many particles as by FFP-3!