Health experts are suggesting stepping up protection against the highly contagious omicron variant with stronger masks such as N95s or KN95s.

The U.S. Centers for Disease Control and Prevention updated its guidance to recommend masks used by health care workers, which offer the most protection against COVID-19, but also noted that it’s important to pick a mask that fit well and that you’ll wear consistently.

The best mask “is the one that you will wear and the one you can keep on all day long, that you can tolerate in public indoor settings,” said CDC Director Dr. Rochelle Walensky.

Previously, the CDC said N95 masks should be reserved for health care workers because of supply shortages.

N95s have a tighter fit to your face than cloth masks and are made with a special material designed to block 95% of harmful particles. The fibers are pressed closer together than in cloth masks and have an electrostatic charge that attracts molecules to stick to the mask rather than passing through.

KN95s and KF94s offer a similar level of protection.

But be careful when buying. The counterfeit market is huge, and about 60% of KN95s in the U.S. do not meet quality standards, according to the CDC.

Experts suggest buying from reputable sellers. Project N95, Grainger or McMaster-Carr are reputable brands.

If you find N95s difficult to wear for long periods, experts suggest exploring different shapes and styles to see what works best for you.