Daiwa Danrotech Undershirt, Extra Thick High Neck, DU-3225S, Black, XL

This underwear utilizes far-infrared technology to adapt to temperature changes during the day and in the morning and evening. The soft, fluffy, and warm fabric envelops the entire body, creating a comfortable environment inside the garment. The hydrophobic (water-absorbent) polypropylene lining prevents sweat from chilling, reducing the drop in body temperature caused by sweat in winter. This extra-thick type is recommended for extremely cold weather and for fishing, where movement is limited.

Danrotech: A Wearable Fireplace - Extra-thick Type for Extreme Cold Weather