The Under Armour Women's ColdGear Armour Compression Mock is a top-selling base layer top on Amazon. It is designed to keep you warm and comfortable during your runs. The compression fit provides a snug and supportive feel, while the ColdGear fabric traps heat and wicks away sweat to keep you dry. The mock neck design offers extra coverage and protection against the cold. This base layer top is perfect for layering under your running gear or wearing on its own. It is available in a variety of colors and sizes to suit your style and fit preferences.