This specially processed fine ceramic product warms you up, giving you the feeling of soaking in a hot spring. While hot springs use geothermal heat, this abdominal warmer uses your body heat, which is then transferred through the ceramics to warm you from the core. In addition, breathable lace netting is used on the sides to prevent stuffiness. Please use it year-round, just like underwear. 95% Acrylic 3% Polyurethane 2% Nylon