Marc by Marc Jacobs Pique Polo Shirt  A black polo is as essential a wardrobe staple as a white dress shirt, but nowadays they have the same purpose—to wear under a tailored jacket. The polo shirt isn't relegated to just the summertime sidelines anymore, and the soft-collared pique knits, like this Marc by Marc Jacobs version, help dress down suits and sport coats in a clean, cool way. Just take a look at Justin Timberlake in the pages of our December issue if you need more proof.  $100, available at Mr Porter.com
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