Aventail

An aventail (/ˈævənteɪl/) or camail (/kəˈmeɪl, ˈkæmeɪl/) is a flexible curtain of mail attached to the skull of a helmet that extends to cover at least the neck, but often also the throat and shoulders. Part or all of the face, with spaces to allow vision, could also be covered. Some featured a ventail (a mail flap next to the mouth) which could be folded over the bottom face and vice versa, much in the same manner as a visor.