Keep your motivation high when the temperatures really drop low. Thermal Weight is our warmest Merino baselayer. It's wonderfully soft, has a great warmth-to-weight ratio, breathes and resists odor, stretches and regulates body temperature across a wide range of conditions. Our fine merino wool is from the grasslands of Patagonia. We slow wash it for softness and shrink resistance without the use of chlorine, then blend it with Capilene® recycled polyester for increased durability, dry times and moisture management. Features include a flat waistband with brushed inner elastic for next-to-skin softness, a gusseted crotch for mobility and low-bulk merrow seams to minimize chafing. Machine wash cold; machine dry at low temperatures. Fabric is bluesign® approved.