HEATTECH Extra Warm is 1.5 times warmer than our regular HEATTECH. We recommended this T-shirt as a layer. Now in plastic-free packaging. - Bio-warming, insulating, anti-microbial, moisture-wicking, deodorizing, and moisturizing comfort features. - Stretch fabric offers a soft texture with excellent shape retention. - The V-neck is deep, but not so deep that you can see shirts worn underneath.