Stargazers looking for a special pair of glasses to watch the upcoming solar eclipse can get a special deal from Warby Parker.

The retailer will be giving out free solar eclipse glasses starting April 1 because they “want to make sure you have everything you need to safely witness this celestial spectacle,” which will be visible to an estimated 31 million Americans on April 8, reports USA TODAY.

Warby Parker will provide two pairs of eclipse glasses per family, and prospective customers can pick up the glasses starting Monday, April 1. Glasses will be available through Monday, April 8, the day of the eclipse, while supplies last. You can see a list of Warby Parker locations here.

READ MORE: Total solar eclipse on April 8: Why this eclipse will be much different than the 2017 version

What are eclipse glasses?

Experts recommend you use specialized eyewear made to protect your retinas. Often designed with polyester film coated and coated in aluminum, certified eclipse eyewear is designed to block all visible, and infrared light. Solar eclipse glasses must be from an approved vendor the American Astronomical Society.

Where else can I get eclipse glasses?

Eclipse websites like American Paper Optics, GreatAmericanEclipse.com and NationalEclipse.com sell a variety of eyewear products. Amazon also sells eclipse glasses in bulk. The American Astronomical Society maintains a curated list of approved vendors. Libraries also offer eclipse glasses.