The Kyanite base layer is designed for cold days and mixed-weather outings. On the move, Polartec® Power Stretch® Pro stretches for exceptional freedom of movement. During rest phases—or when it's really cold—the fleece's soft, brushed interior traps heat to keep you warm. The fleece's durable nylon exterior has a smooth face for comfort under layers, and a zippered thigh pocket stores small essentials.