1937-1pcp, WX88, 1937 U.S. National Christmas Seals, Progressive Color Proofs, perf. 12x121/2, disturbed gum, P4S, NH.
A complete set of seven (7) stages showing color plate separations and the final design. Scan is an example of the item.
Issued by the National Tuberculosis Assoc. (NTA).
Progressive Color Proofs are usually issued in sets to show colors separately and in combination.
Christmas Seals are also known as TB Charity Seals, and are usually classified as Charity Seals, or Cinderella Stamps.