(NEXSTAR) – Last week, the Biden administration unveiled a new program making 400 million N95 masks available for free to Americans after health officials encouraged the use of these masks over cloth face coverings to combat the omicron COVID-19 variant.

The masks are coming from the federal government’s Strategic National Stockpile where more than 750 million of them are stored. Unlike the free at-home COVID-19 testing kits being delivered to your door, you’ll need to head to a pharmacy or community health center to pick up your free masks.

Ahead of President Joe Biden’s announcement regarding the free masks program, the Centers for Disease Control and Prevention issued updated guidance stating properly fitted N95 and KN95 masks offer the most protection.

Where to find the free masks

Nexstar reached out to major pharmacy chains to see if they’re participating, when they’ll be starting distribution and how you can get your free N95 masks. Americans are limited to three free N95 masks per person, according to the Biden administration.

Albertsons: Albertsons, which owns Safeway, Vons, Tom Thumb and more, confirmed it will be participating in the federal government’s mask giveaway “in the coming weeks.” A spokesperson said the company is still working on its distribution plan.

CVS: CVS said it would start providing free N95 masks as part of the program “as we receive supply from the Federal Government.” The pharmacy chain did not provide any details on timing.

Kroger: A spokesperson for Kroger, the parent company of Fred Meyer, Food 4 Less and more than a dozen different stores, told Nexstar its locations with pharmacies are participating in the program. The nation’s largest grocery chain anticipates its allotment will arrive later this week. Customers are encouraged to visit their nearest pharmacy store for theirs.

Rite Aid: Rite Aid said all of its locations will be participating in the program with some stores starting to distribute the N95s this week. All stores should have masks to hand out by early February, a spokesperson said. Customers will be able to pick up three masks per person at a display in store or at the pharmacy counter, supply permitting.

Walgreens: The pharmacy chain said it will start handing out N95 masks in several sizes at stores starting Friday, Jan. 28, adding more participating locations in the following days and weeks. Stores where masks are available will have signage indicating they’re in stock, a Walgreens spokesperson said.

Walmart: Walmart, as well as Sam’s Club, will also provide free N95 masks, according to CNET. Both companies, owned by Walmart, are part of the Federal Retail Pharmacy Program.

Wegmans: A Wegmans spokesperson told Nexstar the company would be participating in the federal N95 program, but was “awaiting further details” at publication time.

For a list of other retail chains and pharmacies participating in the Federal Retail Pharmacy Program, click here.

What to know about N95 masks

Early on in the pandemic, N95 and KN95 masks were in short supply, prompting the CDC to encourage them to be prioritized for health care workers. In its mid-January update to masking guidelines, the CDC removed its concerns about a short supply.

Instead, the agency now recommends N95 or KN95 masks, saying they offer the most protection against COVID-19.

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.

Dr. Erica Swegler of Austin, Texas, told Nexstar’s KXAN that cloth masks became more obsolete when the delta variant appeared.

“The delta variant somehow had been able to evade that [cloth mask] barrier quite nicely, and it is just not sufficient,” Dr. Swegler said. “Somehow, [the virus] is able to penetrate through a plain cloth mask.”

Instead, she suggests wearing an N95, a KN95, or a disposable surgical mask.

The Associated Press contributed to this report.