-Size Medium = Size 12 measures 44 inches around chest, this is a good fit for person with 40 inch chest or less.
-Size Large = Size 14 measures 46 inches around chest, this is a good fit for person with 42 inch chest or less.
-Size XL = Size 16 measures 48 Inches around chest, this is a good fit for person with 44 inch chest or less.
-Size XXL = Size 18 measures 50 inches around chest, this is a good fit for person with 46 inch chest or less.
-Size XXXL = Size 20 measures 52 inches around chest, this is a good fit for person with 48 inch chest or less.