The NEW K1 FLEX Tech Layers are constructed of the highest quality blend of 100% Nomex and natural viscose fibers. This innovative material construction offers not only superior flame resistance and protection against heat transfer, but is the ultimate choice for soft, lightweight comfortable underwear. Designed and tested specifically by top pros in Rally Cross, WEC and other endurance challenge series, the K1 FLEX Tech Layers are quickly becoming the top choice of racing underwear throughout all forms of racing.