Merino wool is the cream of the crop when it comes to layering materials. It has a crazy warmth-to-weight ratio, it's breathable and moisture wicking, and it stays warm even when it gets wet. A good merino baselayer sets up the whole layering system to be warm, active, and effective. Backed by all of the super-soft natural fabric, the Helly Hansen HH Merino Mid Baselayer Set is cozy as can be.