Boody Body EcoWear Men's Brief - Athletic Cooling Underwear for Guys Rayon from Bamboo With no seams and a wide waistband these briefs give you full range of motion and fantastic support Moisture-wicking, ultra-breathable and thermo-regulating Great for sensitive skin Ultra comfortable and naturally cooling fabric 80% Rayon made from bamboo 13% nylon. 7% spandex.