Thermal underwear bottom is made of soft fleece lining for excellent comfort and warmth in cold weather. Stretchy elastic and lightweight design for style and function. Two-component fiber is silky (smooth) outside and fleece inside - pleasant to the body. Fabric is wicking moisture and drying much faster than any other material. thermal pants is elastic - provides perfect fit. All seams are flat-lock for high comfort when wearing - eliminates rubbing and pressing with seams. thermal underwear pants has inserts of breathable perforated tissue, providing additional thermo regulation. Can be worn either as standalone or in combination with other layers of thermal clothing, allowing you to achieve perfect level of comfort and thermal regulation