18 Gauge Steel Body Armor Breast Plate By Nauticalmart This is a Extra Large Size Medieval 18 Gauge Mild Steel Body Fluted Cuirass. Cuirass is formed of a single piece of metal or composed of two or more pieces, which covers the torso of the wearer. The term cuirass commonly is understood to imply the complete body-armour, including both the breast and the back plates. This cuirass has lines of fluting on its breast and back plates - both are crafted from 18 gauge mild steel. Comes with 6 adjustable(0.25" to 2.25") leather straps hold the cuirass together and are used to fit and adjust the armor to the body.