I just received these shirts from Purchase Officials in a extra large and these shirts are HUGE! They measure 27 inches from seam to seam at the underarm and the sleeves are over 12 inches from the shoulder seam to the end of the sleeve. The extra large is comparable to a XX. I'm happy with the quality of them, they're made of the pebble knit and seem to be very sturdy. My only complaint is that they're HUGE and I would of sent them back for a Large if I wouldn't have already washed them.