1973-4px, 1973 U.S. National Christmas Seals, Imperforate Proof Sheet of 100 seals, pm "B", full gum, F, MNH. Fresh, firm paper, vibrant colors, never folded, shipped flat. Scan is an example. Full scan of front and back available upon request.
Issued 1973 by the American Lung Association (ALA). Designed by Cheryl Johnson. Images of twelve (12) designs representing the Twelve Days of Christmas. Printed by I.S. Berlin Press.
Imperforate sheets have no perforations or rouletting at all.
Christmas Seals are also known as TB Charity Seals, and are usually classified as Charity Seals, or Cinderella Stamps.