It is a bridle used for high level dressage that has two bits: a curb and a snaffle. The rider uses two sets of reins and communicates to the horse differently with the curb bit(weymouth) and the snaffle(bradoon). It is used after riders have ridden many many years and have very light hands. At this level the rider uses aids from their body, legs, arms and pretty much every part of their body to communicate to the horse at a very subtle level and the two bits are incorporated in that.
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