When it's bitingly cold outside, layer up with the Under Armour Women's Base 4. 0 Crew. Made with Mega grid fleece, this low bulk top provides huge warmth without weighing you down. Armourblock anti odor technology fends off funky odors, and flatlocked seams provide a comfortable fit. The fitted design keeps it tight enough pull moisture away from your body, but loose enough that you don't get the uncomfortable squeeze of a form fitted layer. Built in thumbholes keep the sleeves from bunching when you layer overtop.