'Breastplates' in the Bible

they had chests like iron breastplates; the sound of their wings was like the sound of chariots with many horses rushing into battle;

This is how I saw the horses in my vision: The horsemen had breastplates that were fiery red, hyacinth blue, and sulfur yellow. The heads of the horses were like lions’ heads, and from their mouths came fire, smoke, and sulfur.