combined with chemical cartridges. Should be combined with prefilter SR 221, which will thereby extend the life of the particulate filter. The SR 510 P100 particulate filter is high efficient filter of mechanical type. It protects against all types of particles (dust, fume, fog, spray, asbestos), even bacteria, viruses and radioactive dust. This filter can be used with all Sundstrom Air Purifying Respirators.