A Mystery Box is a factory-sealed signed shirt whose signatory stays undisclosed until the box is opened. The mystery is the name, never the signature.

The FC Barcelona Mystery Box shows how the format works. Inside the sealed box is an FC Barcelona Nike home shirt signed by one of the club's own players. Which player stays unknown until you break the seal. What is known is the part that matters most to a collector: ICONS witnessed the signing and issues the certificate of authenticity for it, so the signature is certain from the moment it was made, not judged after the fact.

Because the seal stays unbroken, nothing more can be said about the shirt inside than ICONS has certified, and that is deliberate. The uncertainty is the format, not a gap in the paperwork. Whoever it turns out to be, the shirt is a genuine signed FC Barcelona piece, and the moment of opening is part of what you are buying.

For signed shirts where you know exactly who you are getting, see the Luxury Gift Box, which carries officially licensed ICONS signings, and the Luxury Frame.