When buying a respirator mask on Amazon, it’s tough to know you’re getting a good one. WSJ put eight N95 and KN95 masks to the test and found not all tested at the required 95% filtration efficiency. Here are experts’ tips for spotting a lesser quality mask. Photo illustration: Ryan Trefes More from the Wall Street Journal: Visit WSJ.com: http://www.wsj.com/ Visit the WSJ Video Center: https://wsj.com/video On Facebook: https://www.facebook.com/pg/wsj/videos/ On Twitter: https://twitter.com/WSJ On Snapchat: https://on.wsj.com/2ratjSM #Covid #N95 #WSJ