Either you know it or not, Base Layer is the key to any successful outing. Vitalizing on their ColdGear infrared and their Scent Control, Under Armour has become of the industries most leading line of both comfort and functionality. Base Layer is your "core", it is what helps keep your body temperature articulated and controlled. On a hot day it helps keep you cold and on a cold day it helps you stay warm. Topping that off with their Scent Control that helps keep all of your scent out of the game is what makes these one of if not, the best base layer out there. Under Armour is the ones who started the Base Layer industry and you know that they are here to stay. If you don't have any, get a pair and you will never wear anything else.