Mail Collar is a type of neck protection that can be closed by buckles or hooks. There are similar types named pizane, mail standard, mail cape, and bishops mantle. They share the construction of angeled segments with typically five to seven seams.
These segments help to achieve the circle. When an angeled edge meets a smooth edge this leads to expansions built into the seam. This seam is referred to as gusset-seam. At the very front two angeled edges meet. Consequently, there are twice as many expansions in one place. This can be elegantly connected by a turn-seam.
The neck section of medieval mail collars is always denser than the lower parts. This density improves the protection but also stiffens the mail. With that, it can stand up and stay in place. The dense weave is achieved by a regular 4in1-pattern but with stronger rings. Only in some rare exceptions, there is a 6in1-weave. Sometimes the dense mail can extend further down the front – especially in Bishop mantles. Yet of course it is easier to do the 6in1-weave unless you are in a position to make your own rings with the desired strength.
Recently Charles Lin wrote an article about building a mail collar on his blog. There you find more pictures and explanations of the construction. To learn more about the seams, read the seams-chapter.