Lying flat down approx. size measurements unstretched:
Medium
Shoulder: 19 inches/48.3 cm.
Armpit to armpit: 21.5 inches/54.6 cm.
Sleeve: 25 inches/63.5 cm.
Back center length(bottom of collar to hem): 25.5 inches/64.8 cm.
XL
Shoulder: 20.5 inches/52 cm.
Armpit to armpit: 24 inches/61 cm.
Sleeve: 25.5 inches/64.8 cm.
Back center length(bottom of collar to hem): 26.5 inches/67.3 cm.
2XL
Shoulder: 21 inches/53.3 cm.
Armpit to armpit: 25 inches/63.5 cm.
Sleeve: 26 inches/66 cm.
Back center length(bottom of collar to hem): 27 inches/68.6 cm.