De Rong De Rong is an acrylic fiber, and the bottoming shirt made of it is soft to the touch, good in warmth retention, excellent in color fastness and sweat absorption. Modal is a kind of regenerated cellulose fiber, which has higher strength than ordinary viscose fiber and can be woven into thinner cloth, but it also loses the warmth of the bottoming shirt, so the bottoming shirt has good delong.