1938-3px, 1938 U.S. National Christmas Seals. Imperforate Proof Sheet of 100 seals, pm "D", F, No Gum. Firm paper, fresh, never folded, shipped flat. Scan is an example. Full scan of front and back available upon request. Label is not attached to sheet.
Issued 1938 by the National Tuberculosis Association (NTA). Mother and two children at window. Portrait seals at the four corners. Sheet of 100 (10x10), 96 regular and 4 portrait seals. Seal colors: brown, red, green, and black. Edwards and Deutsch Litho Co., there is an 'D" in the lower right corner of seal #56.
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.