These are wedding invites, of which the information on them, like date and location were only visible when wearing the supplied red lens glasses. Such a sweet idea. 

joelaz:

Save The Date Decoder Glasses

The Save The Date card for our wedding included a pair of red shades that you needed to put on to decode the invite like the one pictured above. It also included a request for invitees to email a picture of themselves wearing the glasses to a special email address that posted them on our wedding website. These are just a few of the photo responses we received. Interactive & fun! Thanks to Ming Thompson at Pounding Mill Press for working with us on the design.