'Breastplates' in the Bible

They had breastplates like iron breastplates, and the sound of their wings was like the noise of many horse-drawn chariots charging into battle.

Now this is what the horses and their riders looked like in my vision: The riders had breastplates that were fiery red, dark blue, and sulfurous yellow in color. The heads of the horses looked like lions' heads, and fire, smoke, and sulfur came out of their mouths.