Coldpruf Basic Midweight Underwear Crew Shirt - Men's, Winter White, X-Large 2 Layer Engineering Traps Air Between Layers Providing A Natural Barrier of Warmth INSIDE and OUTSIDE: 60% Combed Ring Spun Cotton, 40% Polyester The BASIC has been designed for wear in cold to very cold weather with low to medium activity. DELIVERS COMFORT AND WARMTH IN ALL COLD WEATHER ENVIRONMENTS - WHETHER AT HOME, ON THE JOB OR ENJOYI