"ARMET. A type of closed helmet that conforms to the shape of the head and covers it completely. It first appeared on the Continent in the third quarter of the 15th century, and was a very distinct advance on any of it predecessors, being lighter and at the same time completely protecting the head, face and neck. It was soon further improved adding a gorget wide enough to bring the weight on the shoulders instead of the head. As it fitted closely to the shape of the head it was necessary to open it in order to put it on. In the earliest forms this was accomplished by hinging the cheek pieces immediately below the visor pivots so that they could open outwards. The cheek pieces joined in front of the chin, and the visor fitted over them when lowered. The skull piece was continued down the back in a strip about an inch wide which was overlapped by the cheek pieces when closed. A short stem with a disk or roundel, sometimes called a volet, on it projected from the back of the helmet."
* Stone 1934 p93
"BARBUTE. A variety of salade, 15th century. It fits closely to the head and is precisely like the Greek casque. It is usually considered the same as the Italian celata. Some authorities question this.
"Some have a large opening in the front leaving most of the face uncovered; others have fixed nasals; others again have a T-shaped opening that allows the wearer to see and breathe well, all still completely protects the face. It is the best of the open helmets of the time as it covers the head and face completely, is light and not likely to be knocked out of place."