This is an unusual Infantry First Lieutenant's shoulder strap likely made just prior to World War Two. The key to dating this strap is the grosgrain material of the field. That kind of material was never used on Civil War period straps. I have seen straps like this one offered at shows as Civil War. The bars abutting the border is the unusual feature. Specifications written for the Army dress blue uniform in 1938 call for the bars to be five-eighths of an inch and therefore not meeting the border. Telling the difference between Civil War and Post-Civil War straps is more of an art than a science. A collector of Civil War straps needs to know what post-Civil War straps looked like. I see large numbers of them sold as Civil War at shows. If you got this right you are off to a good start. Try to next one. Good luck.