Zip up in cold weather and zip down when it warms up in this year-round favorite, their Men's Merino 150 Base Layer 1/4 Zip. This top uses their lightest-weight Merino fabric wrapped around a nylon core to increase durability, while still keeping the 100% soft, Merino wool you love next to skin. Side seams help minimize chafing while wearing a pack and offer a body-enhancing fit. Select colorways feature a more responsible plant based dye technique. This base layer is comfortable, powerful, sustainable, and, frankly, do-it-all-able.