What is a cloth scarf worn at back of knights helmet?

There may be more than one answer, but one I know is puggree.

The American Heritage Dictionary of the English Language, Fourth Edition, 2006, defines PUG·GREE as: "a cloth band or scarf wrapped around the crown of a hat or [sun] helmet." The Word comes from the Hindi pagri, a turban. I originally encountered this Word in a book about the French Foreign Legion, whose caps (kepis) were famously equipped with white linen puggrees to keep the sun off the backs of their necks. At sporting goods stores today you can buy caps fitted with puggrees. They aren't attractive, but they're better than skin cancer.