Epaulette insignia pad (Unit number)
A blue velvet circular shield with gold braiding around the outer edge. 39 sewn with gold braid in the center.
According to the SHNH catalog card this insignia appears to have been used by General Baldey in 1867 as a first lieutenant in the thirty ninth regiment of the United States Infantry.
It was then donated to History Colorado by N.H. Baldey in 1917 (daughter to George W. Baldey). George Baldey was a private in the army in 1847-48; a private, sergeant, and first lieutenant, in the 2nd Colorado cavalry, serving in New Mexico, Missouri, and Arkansas in 1862-63; and a major and lieutenant colonel of the 2nd Missouri which would later become the 65th United States Colored Troops. He was brevetted Brigadier General and stayed in the regular army after the war being discharged in 1870. (https://www.geni.com/people/Brevet-Brig-General-George-Washington-Baldey-USA/6000000026228710825)
Embroidered in gold thread on the object: 39