Recently have the scarce Madretsch marked of 1905-10 U.S. size 12. Has same fine design and appearance as the others made in 0s, 6s, and 16s. Noticeably bigger than the common popular Gruens commonly called 12 size although only 0.01" bigger than 10s. Shown here with Louis 14th dial Semithin Gruen Guild 10s 1918. Also with a 1917 Verithin mvnt. Added 16s with 0s photo for comparison.
CORRECTION: Measurement by Thojil prompted me to also carefully measure the so called 12s to be same diameter as the 17 ligne Verithin. Bigger only because a little thicker.