This issue is a variant of Marvel Masterworks: The Fantastic Four (Marvel, 2009 series) #6. There exist further variants.
Collects Fantastic Four (Marvel, 1961 series) #51-60 and Fantastic Four Annual (Marvel, 1963 series) #4.
Printed on the spine is: Marvel Masterworks, VOL. 28, The Fantastic Four, MARVEL. The word MARVEL is printed using a font similar to Palatino/Times New Roman and is not an emblem. On the back cover is "This edition is limited to 528 copies."