2.25 times warmer than regular HEATTECH. Stay toasty even on the coldest of days. - Comfort features include bio-warming, insulating, moisturizing and moisture-wicking. - Shape-retaining stretch fabric. - 2.25 times warmer than regular HEATTECH. - Slightly shorter than full-length sleeves stay hidden under clothes. - Size up and wear it as a T-shirt. - The perfect insulating innerwear for extremely cold conditions.