Kombi Kid's Midweight 2-Layer Merino Wool 1/4 Zip Top is a great thermal underwear piece. This is a great all around weight with the added warmth of Merino Wool to keep you warm, dry, and comfortable in most cold weather activities. Merino Wool is soft, breathable, and low pill that stretches for optimum fit. It wicks moisture to keep you dry and works 5 times faster than cotton. The thermal underwear is designed with flat stitch construction for superior seam strength in addition to flat seams against your skin for added comfort and maximum freedom of movement.