Uniqlo's HEATTECH Extra Warm Cashmere Blend Crew Neck T-Shirt in olive. ‘Extra Warm’ is 1.5 times* warmer than Uniqlo's regular 'HEATTECH.' *Based on CLO values, which indicate the thermal insulation of clothing. Compared to standard 'HEATTECH.' 9% cashmere blend. Luxuriously smooth and fluffy. Using yarn that is approximately half as thin as the yarn used in cashmere sweaters, giving you the warmth of standard Extra Warm HEATTECH with approximately 70% of the weight. Moderately sheer fabric and slightly longer sleeves for easy layering.