NanoDri Sweatproof Undershirts utilize Japanese technology to absorb your sweat on the inside but stop sweat from showing on the outside, all over the shirt, including the sides, chest, back, and underarms, while allowing sweat vapor to escape and cooling you down by evaporative cooling. Made of ultra-soft and luxurious 100% micropolyester, NanoDri shirts wick sweat away from the body three times faster than cotton, and dry even faster. Additionally, the 100% sweatproof membrane in the underarms of this 2.0 version is 3X bigger than the original 1.0 version. This shirt is highly breathable and offers very high stretch.