PXP RaceWear High Performance Racing Underwear is made from a 50% Kermel(R) 50% Lenzing(R) Blend.Kermel(R) is an Aramid Fiber which is inherently Fire Resistant. The structure of the fiber is fire resistant and will never wash out or wear out. Lenzing(R) is also permently fire resistant but it is also is highly heat resistant. Lenzing's natural fibers are moisture wicking making a perfect blend for a racer.Inherently Fire Resistant Made of Aramid Fibers (Kermel(R) is a brand name of Aramid fiber just like Nomex(R) is a brand name of Aramid Fiber) Safer than treated underwear Solution-dyed (the dyed is part of the fiber so the color won't wash out or fade). The fiber structure is round so it is super soft Retains its shape so your underwear won't stretch out and look sloppy and unravel like others. Seams are finished and lay flat so they are comfortable. Quality Sewing and Construction Black and Graphite Grey colors look sharp not like ratty yellowed underwear. Exceeds SFI 3.3 & is legal in all racing sanctioning bodies requiring SFI testing (SFI 3.3 Certification Tag sewn on pants, shirts and hoods) All of this means that it will look great and keep you safe for a long long time. Pit Stop USA offers PXP RaceWear Long Sleeve Underwear Top - Black - Medium 113 at low everyday prices. Be sure to check out all of our products from PXP RaceWear including PXP RaceWear Kermel/LenzingUnderwear and PXP RaceWear Lenzing FRUnderwear and PXP RaceWear PXP High Performance Racing Underwear.