1910-1, WX6, 1910 U.S. Red Cross Christmas TB Seal, F, MNH. The 1910 Christmas TB Seal was issued and sold by the American National Red Cross. There was just one type. Size 22x22mm, perf. 12. Scan is an example of the seal. Scan of front and back available upon request.
Note from Green's Catalog: "The designs this year are spaced extremely close together within the sheet and examples with the designs clear of the perforations on all four sides are scarce."
Christmas Seals are also known as TB Charity Seals, and are usually classified as Charity Seals, or Cinderella Stamps.