Dentec Safety believes that wearing our Comfort-AirNx series N95 reusable elastomeric rubber half mask provides better protection than wearing an N95 disposable respirator, surgical or 3 ply mask or a combination of a surgical mask over an rubber half mask with an exhalation valve. The Comfort-AirNx respirators have been designed to provide an airtight seal and two way filtration as there is not exhalation valve. It is more comfortable, less expensive and safer to use the any disposable respirator. And it will reduce waste helping to save our environment. The smoke test verifies the sealing properties of our Comfort-AirNx.. if the air can get out, it can get in.