UA Base is a system of baselayers, numbered from 2.0 - 4.0, that takes you from cold to absolutely freezing temps. It uses a special negative grid structure to trap heat without adding bulk. Think long underwear, re-engineered for athletes performing at their peak. UA Base 4.0 is built for extreme cold weather and lower activity levels.

FEATURES

• Fitted: Next-to-skin without the squeeze. 
• UA Base 4.0 Extreme Baselayer is the warmest yet, locking in your body's heat to deliver extreme warmth in the extreme cold 
• 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 
• Performance elastic waistband  
• 92% Polyester/8% Elasterell