A bradoon is a snaffle bit designed specifically for use in the double bridle. The bit mouthpiece is usually single-jointed.
It works in concert with a curb bit to make up the formidable double bridle. It is typically a thinner and lighter bit than a typical training snaffle. Since there is both a need to reduce the quantity of bitting material in the horse’s mouth, and the expectation that the horse will not be leaning on the bit as much as a less-advanced horse might.
The circumference of a bradoon mouthpiece is typically in the 12-16mm range, and the rings are generally 55mm in diameter, which is smaller than a regular training snaffle.