Shoulder Straps of the post-Civil War period are much less likely to have multiple borders or those that alternate dead and bright bullion than those of the Civil War period. They tend to be better made and have a finished bottom. Often they are marked with manufacturer's or military outfitter's names.
This strap is dates from the 1902-1912 period. It has a quarter-inch all dead bullion borders. The bars ar silver and the field medium blue melton wool. The back is finished off and has clips to attach to the uniform.
This strap has a quarter-inch coarse all dead bullion border. The silver first lieutenant bars identify it as a strap made after 1872. Prior to 1872 they were gold in color. The infantry light blue field was used until 1886 when it was changed to white to match the branch color of enlisted men's chevrons.
This strap has a quarter inch all dead bullion border. The silver first lieutenant bars identify it as a strap made after 1872. The infantry white field was used 1886-1902. After 1902 it was changed back to light blue. Unlike the prior first lieutenant's strap the bars of this one do not meet the border. The regulations did not address this and the bars of the straps may or may not meet the border according to the whim of the manufacturer.
This strap was three-eighths inch all dead bullion borders, which were regulation after 1912. The field is yellow melton wool. Straps of this type were in use prior to 1912.