If you plan to view the total solar eclipse coming April 8, eye safety should be top of mind. Warby Parker, the popular prescription glasses shop, is making it a little easier by offering free solar eclipse glasses at its stores.
The deal started April 1 and will run until eclipse day or until supplies run out. They’ll be limited to two per family. To find a location near you, use this store-locator map and plug in your ZIP code.
In an FAQ on its website, Warby Parker says the glasses it’s giving away were manufactured by American Paper Optics, which is listed on the American Astronomical Society’s preapproved list of sellers that make legitimate (i.e. safe) eclipse glasses.
Read more: Are Your Solar Eclipse Glasses Safe to Use, or Fake? Here’s How to Find Out
Another good option for finding free solar eclipse glasses is to visit your local library to see if it’s offering any. The AAS even has a map of libraries offering certified glasses.
If you get to a Warby Parker store in April and it’s already run out of eclipse glasses, the company says it also has pinhole projectors on hand. You can also make your own pinhole projector.
Wherever you get your glasses, especially if you buy them from a source that hasn’t been vetted specifically by the AAS, it’s a good idea to give them a test run before the big event. To help you figure it out, the American Academy of Ophthalmology says that while looking through them, no light of “ordinary brightness” should be visible through your eclipse glasses or solar viewer; only the sun or sunlight that’s reflected somewhere.
For more on solar eclipse eye safety and where to find glasses ahead of time, here’s what an optometrist would like you to know. Also, read more about the path of totality and what to expect this April.