p2p 19"
sleeve 26"
length 25.5"
The shoulder is sort of semi-raglan so the measurement (15") seems a lot narrower than it is, it fits in the shoulders like a regular small.
It fits pretty much like the other +J stuff in size Small, I'm a 37" chest and it fits me well.
As far as composition goes I'm not 100% sure since I don't have the tags any more, but I'm pretty sure it's 80% wool 20% polymide like the rest of the +J heavy gauge stuff.