Duofold by Champion Varitherm Boys' Thermal Underwear_Black Single-layer 5.5-oz. 96% polyester/4% spandex with 360-degree stretch and quick-drying moisture control Importado Single-layer 5.5-oz. 96% polyester/4% spandex with 360-degree stretch and quick-drying moisture control Ankle length for full coverage, with non-chafe flat-lock seams. Soft mid-weight jersey fabric traps warmth for thermal protection, wicks moisture for sweat-free comfort, dries quickly to chase away chills, even helps control garment odors. Resists pilling, too, for longer lasting wear! 360-degree stretch provides ultimate ease of movement. Tag-free elastic waist adds extra moisture control.