White Fire Retardant race Socks. Certified to SFI 3.3 standards. 180gr Flat seam construction to reduce pressure points. Interlock wave construction for enhanced safety. Latest Fire Retardant Soft Knit Fabric. Flame-retardant underwear is essential for providing the last line of defence in a fire. The extra layer of flame retardant material is an item that no driver should ever have to use, but, if you need it, you will be glad you have it