To those unfamiliar with the concept, a shacket is the technical term for the sartorial sweet spot that occurs when the optimum elements of a shirt and jacket are combined. This best-of-both approach produces a transitional staple that’s the perfect piece to segue you into your spring wardrobe. Wear it over a knit on colder days, or team with a tee when it’s a little warmer. Just don’t call it an overshirt.