Unlined collar, no chest pocket, mother of pearl buttons, and side seam gussets.  The Brooks Brothers Original Polo Shirt is an iconic Trad / Ivy League style item.

 New Without Tags Brooks Brothers Pink Supima Cotton Oxford Cloth Button Down Original Polo Shirt. Made in USA.  Retail $140. 

Regent Fit, which is slim.  Approximate measurement across chest at armpit level by neck size:

14.5  20

15     21

15.5  22

16     23.25

16.5  24

18     26.25

19     28

I combine shipping.