Is the Seal 1/4-Zip a cold weather base layer? Yes. Is it an early season outer layer? YES. How's this possible? The Seal brings together two of our favorite things: Algus CoolTouch™ fabric for the sleeves, and moisture-wicking, odor-fighting Merino wool for the body. It's quickly going to become one of your go-to pieces all year round, it's that versatile.