Great condition. There is no material tag; it feels like rayon. This is oversized for a small. Please see the photos and measurements below.

When flat, armpit to armpit measures 24 inches. 
Shoulder seam to shoulder seam is 22 inches. 
When flat, shoulder seam to the bottom of the arm sleeve measures 21.5 inches.  
The measurement from the top/back collar seam to the bottom of the shirt is 31 inches.  
This shirt comes from a smoke-free home. Thanks for looking!