HEATTECH Extra Warm is 1.5 times warmer than our regular HEATTECH. We recommended this T-shirt is used as a layer. Now in plastic-free packaging. - Bio-warming, insulating, anti-microbial, moisture retention, moisture-wicking, deodorizing, and moisturizing comfort features. - Stretch fabric offers a soft texture with excellent shape retention. - This item was designed to be used as either inner or outerwear, and the cuffs feature two-needle stitching.