The "Mantles" first referenced by the English in the 1530s are what the Irish of the period called
an brat (sing.).
These garmets functioned as a thick sleeping bag/cloak that traveled with you for those wet Irish nights outside the tower house. It provided refuge from wet and cold. It is interesting to think about; there are no documented tent like structures for
na buannaiti during 1500-1599. No evidence of them using the guerrilla warfare tactics of the rural
ceithrenn to acquire such structures from the invading English or buying them from the Spanish. So, these guys were most likely camping under the stars every night in their
bratte.
These differ in size and style based on your 16th c. character's place in the world. The richer you are, a tabby woven, tough (melton cloth and the like) and clean semi circular piece fabric is what you would have had. This is because if your a lord or the relative of said lord, you are probably sleeping on the top floor of a tower house not the wet ground. Unless you are traveling on foot to a battle. The rougher/tougher slightly poorer
buannadha or
ceithrenn would have worn something with a Flokati rug like knap. That knap on a fabric would provide a wonderful surface to deflect water during a cold night on the grassy Irish ground the night before a battle.
The Irish from 1300-1590 used to make this amazing Flokati like fabric. It's exact origins and construction techniques are now unknown, but, such
bratte (pl.) are clearly documented in said time period. We see L. De Heere's and other pictures from the 1530s depicting the clearly richer
buannaiti wearing the tougher fabric
Bratte. The common Éireannach of J. Derick's woodcuts (this being a rather lousy reference, but, a period woodcut none the less) are shown weaing the Flokati like garmets.
Aesthetically, to us modern steel and history junkies; the Flokati style
bratte are WAY cooler looking than the plain woven fabric. This is one of those things where you must consider the moment in the past. In the Renaissance, loom woven fabric was the more expensive making it more fashionalbe to those who could aford it (the all too well known 16th. c cliché "the clothes make the man").
Questions, if you have any, please ask. I have been known to attempt an answer at a question and miss it by an inch

more like a mile
Hope this helps.