Duofold Protherm Women's Long Sleeve Crew # 231A base-layer-underwear closure Single-layer polypropylene fabric provides moderate-level warmth, for comfort in colder weather. Better yet, it wicks away moisture to head off sweaty chills. Even helps control garment odors to keep you feeling fresh. Allover ribbing adds natural stretch, for flattering, shape-keeping fit. Details add extra value: neatly bound crewneck; cozy ribbed cuffs; no-chafe flat-lock seams. 100% polypropylene