Shop boys' underwear in red, blue, green, yellow, gray, and many more interesting colors. Under Armour offers a plethora of products ranging from clothes to headphones and watches. The brand is immensely popular amongst power athletes who strive for perfect outwear clothes for training and important sporting events. Gray is the perfect combination of dark and light colors. Durable or fancy? Look or feel? What you want in your Under Armour Gray Underwear for boys depends on materials like Blend and Polyester.