20-1x, WX26a, 1920 U.S. Christmas Seals Sheet, Type 1, F, No Gum. Sheet never folded, shipped flat. Scan of front and back.
Issued 1920 by the National Tuberculosis Association (NTA). The NTA Issued Christmas TB Seals 1920-67. Designed by Ernest Hamlin Baker. Image of Santa carrying child on his shoulder. Type 1, sheet of 100 (10x10), union label, red, green, and blue. Seal size: 18x22 mm, perf. 12. There are four circles at left of seals #31, #41, #51, and #61. Type 1 seals were printed by Eureka Specialty Printing Co.
Christmas Seals are also known as TB Charity Seals, and are usually classified as Charity Seals, or Cinderella Stamps.