Shop boys' underwear in red, blue, green, yellow, gray, and many more interesting colors. Under Armour is a prominent US-based sports equipment and clothing apparel brand. It was launched in 1996 by its founder Kevin Plank. The brand is operational in 15 major countries across the world with over 15000 retail stores. Red is the single most dynamic and passionate color. Best selling Under Armour Red Underwear for boys are available in an assortment of fabrics like Blend and Polyester. Shop what appeals to you with ease from top brands and retailers.