Xtremen Size Chart Xtremen men’s underwear is designed to provide the best of style and endurance. Every Xtremen men’s underwear style is made from high-quality fabric and innovative design. Fabrics include stretch microfiber, athletic micro mesh, and a cotton mesh blend that ensure long lasting comfort and amazing support. Xtremen men’s underwear come in trunks and boxer briefs, the ideal underwear to wear every day, when comfort is key and style is essential.