My wife bought this in 2006 at their Pittsburgh show. She told me it's a men's Small since the Medium looked a little big and she did take the inner tag out. I'm 6'3 and just tried it on and it's pretty tight on me so I agree it's either a men's M or S and based on measurements below I'd go with Small just to be safe. There are a few small white bleach stain marks in center area but nothing major at all. If you wear a Large or XL this one might not be for you just being honest but still fit me just very snug and I wear M and L all the time. (see pics)

Measures roughly 17.5 inches wide and 24 inches long.