What's a "Hang 10" ?

If anyone has a good picture of the Hang 10 package, I'd like to see it.......figured it had something to do with the "mod" craze back then, and the fold down makes sense............

Anybody have a picture of the interior?.............And why would some guys advertise a Grille as a "Hang 10" ?............No different than the others, is it? :read2: