The Sparco Ice Nomex Undershirt feature a unique panel construction for the most comfortable fit. By moving the seams away from the sides, an even more tailored fit is possible. The Ice line of Sparco Soft-touch Nomex Underwear utilizes Sparco's unique X-Cool treatment. X-Cool is a chemical treatment applied to the fabric consisting of micro capsules that are freed as body temperature rises. These capsules move away from the heat source (in this case, your body), thus lowering the overall body temperature. A by-product of this treatment is a refreshing menthol fragrance that is released as the capsules move.