Functional underwear made of Double Face material is one of the most versatile in the Sensor range. The special construction of the knit and cut allows the underwear to be used both ways, always with different temperature properties. The side marked as "plus" has a surface made of micropolyester silk, this surface is chosen as an inner, i.e. "on the body" in case of warmer conditions. The Double Face side marked "minus" is made of micropolyester shearling and is chosen as the inner side when used in colder temperatures. The difference in thermal resistance between the two sides of the T-shirt was measured in the laboratory to be 3.6°C.