This chain maille is made of round, butted rings. Their blackened surface provides some protection from corrosion. We call this type of chain maile Butted Mild Steel Blackened.
A haubergeon is a mid-sleeve chain maille shirt that reaches to the thighs.
Details - chest circumference: approx. 140 cm when fully extended. Your chest should not exceed 125 cm when wearing your gambeson. - length: approx. 85 cm - arm length: approx. 29 cm - ring thickness: 1.6 mm - interior diameter: 8 mm