Size marked L. Fits close to a 42R based on measurements.
100% Cotton

Measurements:

Chest: 21.25" (armpit to armpit) 
Waist: 20.5" (measured across waist) 
Shoulder: 18" (shoulder seam to shoulder seam) 
Sleeve: 24.5" (shoulder seam to sleeve cuff) 
Length: 28" (bottom of collar to bottom hem)