Aventail

An aventail (/ˈævəntl/) or camail (/kəˈml, ˈkæml/) is armour consisting of a flexible curtain of mail attached to the lower part of a helmet that extends protection to cover at least the back and sides of the neck. Parts of the face, throat, and shoulders could also be covered, with spaces to allow for vision. Some featured a ventail (a mail flap next to the mouth), which could be laced or hooked up to cover the lower face, or left loose to facilitate breathing and speech.