The Sensor DOUBLE FACE thermal underwear belongs among the most universal pieces by Sensor. A special construction of knit and cut makes it possible to use the clothes on both sides with different thermal properties. The side marked as "plus" has a surface made of micropolyester silk, so it is suitable as an inner side in warmer conditions. The side marked as "minus" is made of micropolyester staple, which makes it perfect for colder temperatures. The difference in thermal resistance between the two sides was laboratory-measured at 3.6°C.