I purchased the sealed box back in the late 80s, and it was packed away till mid 2000s. I decided to open the box because I’d always been curious to see the jacket. Label on bottom shows March 1949 date. Jacket is labeled as very lightweight and size 18. I dont believe this size 18 equates to current sizes. I’d say it’s M-L. I’ve rarely seen this jacket online through the years, and recall that the friend selling these only had a large box full. The USAAF was a branch created after World War II. Definitely a piece of history. Jacket never worn.