Duofold Thermals Mid-Weight Youth Long Sleeve Crew # 623C base-layer-underwear closure Mid-weight jersey fabric feels soothing against young skin. (Its cotton-rich for softness, with enough sturdy polyester to withstand tough wear &amp; tear.) Two-ply design traps body heat to create a warm thermal barrier. Ribbed cuffs provide cozy fit. Flat-lock seams wont chafe or dig. Tag-free banded crewneck keeps its shape, wash after wash. Ideal on its own or as base-layer thermal underwear. 60% cotton/40% polyester bi-ply jersey. Samw as 622A