N95 or KN95? What to know about face masks as the Delta variant spreads

Well, it was nice while it lasted, but the Centers for Disease Control and Prevention is about to once again urge people—even those who have been vaccinated against COVID-19—to begin wearing masks again in certain circumstances.

Because the Delta variant is so contagious, though, some health care experts are now questioning the effectiveness of cloth masks. That could lead to renewed interest in N95 and KN95 masks as people look to protect themselves. But if you’re in the market for one, things can get confusing fast. Here’s a quick guide of things to consider if you’re looking to upgrade your mask.

What’s the difference between a N95/KN95 mask and a medical or cloth one?

N95 and KN95 masks offer a much closer fit than cloth masks or disposable medical ones. As we’ve learned, it’s possible to make medical and cloth masks fit better by tying knots in the ear loops, but an N95 will always have a bigger seal.

N95s (and some KN95s) are a type of respirator, filtering out both larger and smaller particles you inhale. Cloth masks, though, are largely meant to prevent the wearer from expelling respiratory droplets.

It often comes down to layers. N95 and some KN95 masks have five layers of protection. A medical mask has three. And some cloth ones only have one.

What’s the difference between KN95 and N95 masks?

With similar names, these two higher-filtration masks have resulted in a lot of consumer confusion. N95 masks are considered the high-bar of face coverings. They fit snugly on the face and are especially effective in filtrating airborne particles, filtering out at least 95% of very small particles.

KN95 masks aren’t approved for use in medical settings, as they’re not regulated by U.S. officials. They’re largely imported from China. But a well-fitted KN95 mask is still extremely effective in stopping the virus, moreso than a cloth or disposable surgical mask.

What is a NIOSH-approved mask—and how can I verify the one I’m buying really is approved?

The National Institute for Occupational Safety & Health, since 2018, has worked with the Food and Drug Administration to approve N95 respirators. (KN95 masks are not regulated.) The list of approved manufacturers changes, so it’s always wise to compare what you’re thinking of buying to the list—even if the sales listing says “NIOSH approved.” Some companies that were once approved no longer are, but they haven’t updated their marketing.

Find the extensive list of NIOSH-approved N95 masks at the organization’s website.

Is there still a shortage of N95 masks?

At the start of the pandemic, officials urged Americans to not buy N95 masks, as there was an insufficient number for even healthc are officials. Many retailers would no longer sell them to non-medical personnel.

That shortage has passed, and consumers can once again purchase N95 masks, though it might be more than they need. Amazon and other sites, however, are once again allowing consumers to buy them (and KN95 masks).

This story was originally featured on Fortune.com