If you don't own a featherweight version of the simple crewneck sweater, allow us to make our case for one now. Ideal for those tricky temperatures that often make dressing between seasons a challenge, they add a layer of insulation on cooler days and crisp evenings. And since they're knit from breezy blends of linen and cotton mixed with touches of silk or cashmere, they're breathable enough to keep you from overheating on sunny days. Right now, you can sport them with a T-shirt and push the sleeves up, but once the real autumn weather arrives, they make easy work out of layering. Which is why we suggest opting for a color that will pair with the rest of your wardrobe—we think you'll be getting a lot of wear out of these non-wool wonders.