1979-3x, 1979 U.S. National Christmas Seals, Imperforate Proof Sheet of 54 (6x9) seals, pm "B", full gum, VF, MNH. Fresh, firm paper, vibrant colors, never folded, shipped flat. Unpriced in Green's Catalog. Scan is an example.
Issued 1979 by the American Lung Association (ALA). Designed by school children from each state, plus Puerto Rico, Virgin Islands, D.C., and Guam. Similar to 1975 with images of children's art of holiday scenes. Printed by Barton-Cotton Company.
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.