Description
The bit was a short bar, usually made of metal, placed in the mouth of a horse. Its ends, which projected from the mouth of the animal, were attached to ropes or leather straps that fitted over the head as the bridle.
Usage

Translation

The Hebrew word mtsilah in ZEC 14:20 probably refers to some sort of noise-making decoration on the harness of a horse. The word occurs only here in the Bible.
In REV 14:20 the reference to “a horse’s bridle” (RSV) is merely an indication of measurement. It refers to the height of the bridle from the ground, so we may render this measurement as “about a meter and a half” (FRCL) or “about five feet” (GNT).
The Greek word used in 2MA 10:29 and 1ES 3:6 indicates that the metal parts of the bridle were made of gold.