Shoulder straps were grade (rank) insignia worn on the ends of the shoulders. Below are those of field officers typical of ones worn during the Civil War.
This is a triple border strap with a relatively small silver eagle incorporating sequins into the design of the wing. The field color is light blue of infantry.
This is a triple border strap with silver bullion leaves. The middle border of the three is raised relative to the others. The lower edge of the leaves touch the ends of the strap's border. The velvet field is scarlet of artillery.
Unlike the two straps pictured above this one has a regulation border. The execution of the leaves is unusual. Metallic silver letters "QM" have been added to indicate the officer is part of the Quartermaster Department. Period regulations do not authorize adding letters to straps but the practice was not uncommon. The field is the dark blue of staff officers.