Purchased the Black
I'm 5'9, 160lb, athletic build. I can wear a M or L depending on the cut. I purchased a medium and it was a bit tight so I returned it for an XL, yes, went up 2 sizes b/c I also knew that after washing, it would shrink a bit.
XL fits great with a short or long sleeve tee underneath. Instructions state NOT to tumble dry and it makes sense b/c this is 80% cotton. I'm a huge fan of TS clothing but the one caveat is that every now and then it might need to be returned for a different size. Reviews help a lot but nothing is perfect when it comes to clothing or our own personal size and tastes. All in all I love this polo.