Shafts (instep supports) // Plastic shafts

The shank or instep support can be made of plastic and sometimes fiberglass. A modern plastic shank greatly lightens the weight of the shoe, but is not inferior in strength to metal. It is also worth noting that a plastic or fiberglass shank is guaranteed not to cause problems when passing control at the airport, but a metal one can "excite" devices and cause you little trouble.