It's a casual revolution of sorts. Even the most sartorially minded gents are pulling on sweatshirts this fall, over their everyday button-down shirts or under their tailored topcoats. And for good reason. Smart style doesn't always have to be so buttoned-up. In fact, nothing personifies this new era of laid-back layering like the latest crop of cleverly designed sweats—sharp, modern interpretations of that humble loop-back pullover. More tailored, with unique design details like contrast pockets, side zippers and Nordic graphic patterns, they're pieces that will easily mix in with the rest of your off-duty kit and look sharp, not slovenly.