The Under Armour Women's ColdGear Armour Compression Mock is a top-rated synthetic base layer top on Amazon. It is designed to keep you warm and comfortable during cold weather activities. 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 elements. This base layer top is highly rated for its performance, durability, and comfort.