SAFETY WORKS Paint and Pesticide Replacement Cartridge and Pre-Filter, Filter Rating: P95, White, Suitable for: SWX Series Full Face pieces or Half-Mask Face pieces RespiratorThese cartridges and pre-filters are approved by NIOSH (National Institute for Occupational Safety and Health) to the P95/OV categoryThe long-life pre-filters are approved to the NIOSH P95 Class, so they are at least 95% efficient against oil- and non-oil based contaminants, and are oil-proof so they have no time use limitationThese cartridges include Pre-Filter covers with narrow openings to retain the P95 pre-filters on the cartridges, and to assist in fit checking the respirator for proper fitThese cartridges are only compatible with SWX series Full Facepieces or Half-Mask Facepieces