... weight, comfortable in wearing, airtight, high filtrating efficiency, huge air flow, easy in operation with remarkable positive pressure, service life, ... m filtrating precision;2) 99.97% filtrating efficiency;3) air flow 170L/Min;4)12 hours consecutive working battery, (rechargeable ... ill odors.And not unsuitable to anoxic (i.e. oxygen content less than 18%) or explosive operating conditions, or ...