New Without Tags Brooks Brothers Yellow Supima Cotton Oxford Cloth Button Down Shirt. Made in USA.  Featuring an unlined collar, no chest pocket, mother of pearl buttons, and side seam gussets.  Retail $140.  Regent Fit, which means Slim Fit.  Use measurements to predict fit.  True color is the second picture, close up of size label.

I measured one shirt in each neck size.  This is P2P (measured across chest at armpit level).

15     21
16     23.5

I combine shipping.