NASHVILLE, Tenn. (WKRN) NASA issued a warning Thursday about unsafe eclipse glasses being distributed by “unscrupulous companies.”  NASA recommends using only eclipse glasses with ISO 12312-2 printed on them that have been printed by the four following companies:

American Paper Optics, Rainbow Symphony, Thousand Oaks Optical, and TSE 17

NASA says buying your eclipse glasses on Amazon does not ensure their safety.

Make sure to check your eclipse glasses and viewers to verify that they have the correct ISO designation and were manufactured by one of the four companies recognized by NASA as legitimate, the agency noted.

It’s unsafe to look at the sun for any amount of time as it can possibly be dangerous and lead to permanent damage, hence why purchasing eclipse glasses is so important.