Elgin pocket watch movement case, glass topped metal box antique vintage

Vintage Elgin - National box to hold a pocket watch movement. No date on this that I could see, probably 1900s - 1920s, I think. (I am not a watch expert, and know very little about this, sorry!)

Glass top and bottom, metal looks like nickel plated brass to me. It's in good clean condition, opens and closes neatly, not a lot of scratching to the glass.