The Extreme Cold Weather Clothing System, or Gen-III ECWCS is a protective cold weather clothing system created originally by the United States Army Natick Soldier Research, Development and Engineering Center. They are used in various combinations to meet the cold weather environmental requirements of the US military.

Tru-Spec's baselayer thermal garments are based off these designs to provide the same level of quality and utility. The Level-1 garments draw moisture away from the skin to the outer layers of clothing, providing great warmth without weight, while being quick drying and compressible to reduce volume when packed.

• Double needle-stitched crewneck collar.
• Thumb holes in sleeves for adding multiple layers.
• Flat-locked construction.
• Microban anti-microbial properties in the fabric to aid in odor defense.
• Double needle-stitched hem.