Gore Running Wear Essential Base Layer WS Boxer 100% POLYESTER, WINDSTOPPERMEMBRANE, STRETCH: 91% POLYPROPYLENE, 9% ELASTANE Imported These running boxer shorts are ideal for windy, cool days Elastic WINDSTOPPER insert in genital and posterior lumbar area Thin and soft fabric Minimized seams for less chafing WINDSTOPPER laminate protects the genital area from wind chill but still provides maximum breathability