'Coats' in the Bible

“Harness the horses,And mount, you riders!Take your stand with your helmets!Polish the spears,Put on the coats of mail!

Sharpen the arrows, take up the shields [and cover yourselves]!The Lord has stirred up the spirit of the kings of the Medes,Because His purpose concerning Babylon is to destroy it;For that is the vengeance of the Lord, vengeance [on Babylon] for [plundering and destroying] His temple.