100% cotton. The tag is marked XXL. The actual measurements when laid flat are:
Pit to pit: 24.5 inches
Top of collar to bottom hem in back: 33.25 inches
I bought this deadstock- never washed or worn. There was, however, a bit of dinge on it from sitting in a warehouse for years, so I laundered the shirt. It looks perfect now, but it has been washed- never worn.
Be sure to check my shop for hundreds of killer vintage tees. And stop back often- I have TONS of stuff not yet listed!