This thermo underwear is made of material which perfectly combine qualites of functional fibre PROLEN andcotton. The functional fibres and cotton are placed into two separate layers which are not interwined. The bodily heat is changing to a perspiration during the movement. The functional fibres-as an inner layer are in contact with the skin- transfer the sweat into cotton layer. The cotton layer due to its absorpive function transfer the sweat from an inner layer very quickly. We managed to separate wet cotton layer from skin which stay warm and dry. Thanks to visible pores in outer cotton layer happen to perfect circulation of air, that is very important for stabilization of bodily heat.