KJV:
And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone.
NASB:
And this is how I saw in the vision the horses and those who sat on them: the riders had breastplates the color of fire and of hyacinth and of brimstone; and the heads of the horses are like the heads of lions; and out of their mouths proceed fire and smoke and brimstone.