'Breastplates' in the Bible

And they had breastplates, as it were breastplates of iron; and the sound of their wings was as the sound of chariots, of many horses rushing to war.

And thus I saw the horses in the vision, and them that sat on them, having breastplates as of fire and of hyacinth and of brimstone: and the heads of lions; and out of their mouths proceedeth fire and smoke and brimstone.