Aventail was a flexible chain mail covering or "curtain", that attached to the sides and rear of a helmet - hanging loose. The entire face was covered, save for an opening for the front. In some variations, eye slits were cut out (thus completely covering the entirety of the face). Also known as Camail, they were often welded or "stapled" on the lower rim of the helmet used. This made their installation permanent. Beginning in the 13th Century, detachable version of Aventails were designed. They will last (in some varying forms) until the early 16th Century.