Millions of people will flood America’s roadways to score a prime spot from which to watch the historic August 21 solar eclipse. To do so without damaging their eyes, they’ll need to wear special sunglasses—and counterfeiters are flooding the market with shady specs. "It's a bunch of unscrupulous people cashing in on the eclipse and putting public safety at risk," Richard Fienberg of the American Astronomical Society tells Reuters.

 So how do you tell if a pair of eclipse shades is legit? “The lenses of fakes allow the penetration of light from such relatively faint sources as fluorescent lamps, while the only thing one should see through authentic solar-safe filters when looking at objects fainter than the sun is pitch blackness,” reports Reuters. CBS adds that legitimate sunglasses should bear the icon "ISO 12312-2."