Pahayag 9:9

Mayroon silang mga baluting tulad ng baluting bakal, at ang tunog ng kanilang mga pakpak ay parang tunog na gawa sa mga karwahe at mga kabayong tumatakbo sa loob ng digmaan.

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 running to battle.