As you can see in the above left photo (with boot on racing helmet), Hidden Boot Cuffs (also known as Nascar Cuffs) give your driving suit the appearance of a normal lower pant leg. It gives your racing 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!
Hidden Boot Cuffs only apply to the leg cuffs (not arm cuffs).