Combat the elements with Rothco’s collection of military layering systems & thermal underwear. As part of the seven-layer Extended Cold Weather Clothing System utilized by military personnel, our ECWCS apparel provides critical protection against extreme cold. Our insulating tactical undergarments, thermal underwear tops and bottoms, and military-styled boxers and briefs make for great base layers. From field missions and tactical operations to outdoor adventures and everyday wear, our dependable undergarments ensure you stay warm and comfortable.