Merino Wool Thermal Underwear Top. The base layer perfected! Its not just any wool it's merino wool, the finest and softest in the world. Merino wool is smooth and comfortable against your skin, breathable, moisture-wicking, and it regulates your body temperature, whether its hot or cold. No wonder serious athletes and dedicated outdoorsmen pay a premium for the stuff. It's worth it at twice the price but an excess inventory buy means you'll only pay HALF what you would elsewhere!