The Under Armour® ColdGear Twist Mock Neck Long Sleeve base layer makes it easy to stay focused on your workout all season long. It features ColdGear fabric that's smooth and fast-drying on the outside and ultra-warm on the inside. The streamlined fit isn't too tight or too loose so it won't ride up or add bulk. And the mesh underarm panels add ventilation where you need it while the mock-neck collar provides extra coverage and warmth.