RaceQuip® SFI 3.3 rated long underwear is knit from a blend of aramid and FRC fabrics to achieve a comfortable fire retardant garment. The properties of this unique fabric structure create a lightweight garment that performs like Nomex® yet is much more cost effective. The Fire Retardant Cotton (FRC) component of the fabric promotes a soft and supple lightweight feel. Since it's hypoallergenic, it won't irritate your skin like some other materials tend to do. This proprietary fabric blend is also superior at wicking away mositure from the skin and dries quickly. All RaceQuip® fire retardant underwear garments are machine washable and retain their shape well. The black color won't show racing stripes (or dirt). Long-john style. All items exceed SFI 3.3 certification and have an SFI tag sewn in place.