The half zip has had a complicated decade. For a while it sat in an awkward space between sportswear and knitwear, not quite committing to either, and a lot of men wrote it off entirely. That was a mistake. Done properly, a half zip is one of the more useful pieces you can own. It layers cleanly under a coat, works over a shirt collar without looking strained, and moves between weekend and smart casual with less effort than almost anything else in the category. The collar detail does real work in a way a crewneck simply cannot. What we look for is a midweight yarn that holds its structure after a few washes, a zip that sits flush rather than pulling, and a fit that does not swamp the shoulders. Merino and lambswool remain the ones to beat. Avoid anything too thin and anything branded across the chest. These are the half zips that get the formula right.