As you can see in the above left photo, Nascar cuffs give your driving suit the appearance of a normal lower pant leg (what is sometimes called a boot-cuff). It gives your suit leg cuff area that "Taylored Look," but underneath (as seen in photo on the right) is a snug fire resistant elastic material that keeps you protected!
Nascar cuffs only apply to the leg cuffs (not arm cuffs).