A/X Armani Exchange long sleeve shirt, sz M (runs small) Black

A/X Armani Exchange long sleeve shirt, sz M, Black, 100% polyester. Great shirt! I’m 5’8”, 150lbs. so you can see for reference how it fits. It is a little snug on me. Could possibly be a size S. Tag says M. If you just slightly smaller than me it would fit perfect. Armpit to armpit is 18 1/2”. Middle of shoulder down is 25 1/2”. Any questions just ask. Thank you for looking!