24-1xA, WX32, 1924 U.S. Christmas Seals Sheet, Plate A, full gum, F, MNH. Never folded, shipped flat.
Issued 1924 by the National Tuberculosis Association (NTA). Designed by George V. Curtis. Image of an Angel. Offset by Strobridge Lithographing Co. Sheet of 100 (10x10), SE4S, blue red, and yellow. Plate A, seal size: 18x24mm, perf. 121/2.
Christmas Seals are also known as TB Charity Seals, and are usually classified as Charity Seals, or Cinderella Stamps.