UA Base is a system of baselayers, numbered from 2.0 to 4.0, that takes you from cold to absolutely freezing temps. It's constructed using a special negative grid pattern with each individual cell designed to trap heat without adding bulk. Think long underwear, re-engineered for athletes performing at their peak. UA Base 2.0 is built for cold weather and higher activity levels. Fitted: Next-to-skin without the squeeze UA Base™ 2.0 Active Baselayer is lightweight, flexible & breathable for high activity performance in cool conditions UA Scent Control Technology to keep you undetected in all pursuits Soft, brushed grid interior traps air against your skin, closely managing your body's microclimate to keep you warm & comfortable Material wicks sweat & dries really fast 4-way stretch construction moves better in every direction Wide, flat waistband with a rise that sits just right on your hips Inside leg: 75 cm 71% Polyester/29% Elasterell Imported