Call it the lovechild of a polo and a T-shirt. The short-sleeve henley is a nice middle ground kind of piece—not as casual as a typical tee but not as preppy as a polo shirt. It's a garment that revels in the details and elevates your off-duty kit. It's the kind of piece that you can layer under a jacket or denim shirt right now and come warmer weather, easily wear by itself. Look for styles cut from soft, quality fabrics in simple, solid colors and finished with smart details like riveted pockets, fisheye buttons or raglan sleeves. Then wear the hell out of it because it pretty much pairs with everything in your wardrobe.