3 ms·
They only provide protection for four hours
by Larrikin 7y ago
They only provide protection for four hours
- hnaccy 7y agoReally? 3M says to replace if they become too hard to breath through or are soiled. http://multimedia.3m.com/mws/media/447121O/filter-change-out-brochure.pdf http://multimedia.3m.com/mws/media/447121O/filter-change-out...