One of three buttons today--I'm not particularly invested in buttons per se, but sometimes I'll come across one that won't let me go, and this one I paid a pretty penny for because I found--find--it a marvelous thing, which I believe I would never tire of looking at. I think it possible that the Delta here is Delta air (founded as Delta Air Service in the 1920s as an aerial crop dusting operation to combat boll weevils infesting cotton crops!) but I'm not sure and haven't found an exact match of the lettering on this photo ID button. For me, it's about how that excellent yellow, and those stars, and the word "Delta" combine to make this unglamorous looking woman, in her glasses and apron over cardigan sweater, seem as if at the center of some important operation--perhaps a secret agent, 745, whose humble appearance disguises her role as mastermind! (Like an icon of the delta between perception and reality!) Perhaps she's really just a phone operator, or a factory worker, or whatever, but to me this badge makes her seem like a star. 

1 7/8" in diameter, in good well used condition, with a nice weight to it, and sturdy pinback.