ALPINESTARS ZX NOMEX SOCKS - BLACK - SIZE M - FIA 8856-2000 Certified to FIA 8856-2000 and SFI 3.3 homologation standards Formula 1 specification underwear, constructed using an innovative flame resistant technology developed by Alpinestars. Lenzing FR is a special natural viscose fiber with unique thermal insulation and permanent flame resistance properties that help prevent heat stress and heat stroke. Special material formulation is more breathable and has better elastic properties than conventional fabrics. Lightweight, seamless construction ensures maximum driving comfort with minimal material encumbrance Fabric construction is extremely soft to the touch ensuring a pleasant feel against the skin.