Gore Running Wear Men's Essential BL Windstopper Boxer 100% POLYESTER,WINDSTOPPERMEMBRANE,STRETCH:91% POLYPROPYLENE,9% ELASTANE, Imported Flat-lock seams Elastic WINDSTOPPER insert in genital and posterior lumbar area Thin and soft fabric Minimized seams for less chafing Soft elastic waistband, brushed on the inside for optimum moisture transport