Very good protection (subjective perception)

The mask fits well, is easy and narrowed the field a barely perceptible. The filter performance seems to be very good, even odors are completely filtered out. As long as the filter is sufficiently clean, breathing is pleasantly light. Meanwhile, the filter is in spite of "particulate pre respirator for 4251" so clogged that breathing is difficult. The pre-filter is designed for a different model with coarser filters, so he obviously brings almost nothing in my application. Neither the filter in the mask nor the pre-filter you can see the pollution, but by inhalation I feel it clearly.

A dust mask I need only very sporadically. Originally, I had assumed that I could use this one much longer. Because of the perceived short shelf I subtract one point. There remain good 4 of 5 points.

I had bought together mask, pre-filter and goggles because Amazons "is often bought" suggested to me that article would fit together. As mentioned above, the pre-filter brings almost nothing. The mask can not put together with the goggles you.