UA Base 4.0 Extreme Baselayer is our warmest yet, delivering extreme warmth in the extreme cold UA Scent Control Technology to keep you undetected in all pursuits Soft, brushed grid interior traps air, managing your body's microclimate to keep you warm & comfortable Material wicks sweat & dries really fast 4-way stretch material moves better in every direction Performance elastic waistband UA Base 4.0 men's cold weather leggings are built for extreme cold weather and lower activity. Their unique pattern traps heat without adding bulk. Think long underwear, revamped for today's top athletes.