... 2.SGS approval 3.High efficiency,low resistance HEPAProfessional in production for HEPA filter net, compound filter, humidification filter (damp ... and reach N99 class. It’s the ideal material for medical and purification industry. Compound filtersThe purpose of ... has the function to purify and absorb the odor substances, for example, ammonia, fluorine, formaldehyde, methanthiol, hydrogen sulfide etc, ...