This is the heavy-duty layer you throw on over a plain white tee when the London weather can't make up its mind. Carhartt WIP has nailed the shirt-jacket hybrid here, using a tough 100% cotton fabric that has been garment-dyed for a washed, lived-in look from the very first wear. It is completely unlined, keeping it light enough for spring afternoons but sturdy enough to block a breeze. You get one clean chest pocket on the outside with the signature square brand patch, plus two hidden pockets on the inside to keep your phone and keys secure without adding bulk to the clean silhouette. The relaxed cut makes it easy to button up fully as a heavy shirt or leave open over a hoodie. It is a straightforward, functional piece that does the hard work for you.