When we're getting the family out for a ski day, snowshoe trek, or wintertime hike, the Under Armour Base 4. 0 Crew Shirt provides consistent warmth during the coldest days of winter. The brushed interior traps warm air close to the body, with exceptional breathability to regulate body temperature as we work up a sweat. The quick-drying, moisture-wicking fabric ensures our kid stays comfortable during high-output activities, and the four-way stretch material allows for a full range of natural motion to tackle any adventure.