The Latin word "manica" means a sleeve. A manica was a type of iron or bronze arm guard, with curved and overlapping metal segments or plates, fastened to leather straps, worn by Roman gladiators called crupellarii, and later by soldiers.
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... Bishop lists likely components as one shoulder plate, about 35 metal (ferrous or copper alloy) strips, 90-120 leathering rivets, 3 or 4 internal leathers, and one padded lining ... The lining may have been a separate component, in order to avoid it being torn by the articulated metal plates ...