Meanwhile, Aegle, a producer of NIOSH-approved N95 masks in Brookshire, Tex., takes a more sophisticated approach. Whether you buy Aegle masks from marketplaces such as Amazon or directly from the manufacturer, each package comes with a tiny chip called an NFC (short for near-field communication) tag built into the box. You don’t need any additional gear to read these tags — most modern smartphones have NFC reading abilities built into them. Just touch your smartphone to the box, and its Web browser will open, showing you the filtration test results of masks from the lot yours came from.