... 3.High efficiency,low resistance HEPAProfessional in production for HEPA filter net, compound filter, humidification filter ... but also add the functions of absorb water, antibacterial and mould proof & air purification.The product ... function to purify and absorb the odor substances, for example, ammonia, fluorine, formaldehyde, methanthiol, hydrogen ... silver masks, exposure suits, hygiene necessities.