Razer sold its Zephyr face mask as "N95 certified," but failed qualification tests and now must reimburse consumers.

As the free N95 masks begin to become available in parts of the U.S., here's what you need to know about getting one.

But choosing which type to use might seem tricky — you could go with a reusable cloth mask, a disposable mask or a respirator, like a N95 or KN95.