A double bridle, also called a full bridle or Weymouth bridle, is a bridle that has two bits and four reins. One bit is the bradoon, is a modified snaffle bit that is smaller in diameter and has smaller bit rings than a traditional snaffle, and it is adjusted so that it sits above and behind the other bit, a curb bit. Another term for this combination of curb and snaffle bit is a "bit and bradoon", where the word "bit" in this particular context refers to the curb.
Double bridle, with both curb and snaffle bits.
A double bridle used in the show ring.
A "bit and bradoon" (curb and snaffle), the two bits of the double bridle
Detail of a "bit and bradoon", long-shanked curb and thin bradoon traditional in Saddle seat style riding
A bridle is a piece of equipment used to direct a horse. As defined in the Oxford English Dictionary, the "bridle" includes both the headstall that holds a bit that goes in the mouth of a horse, and the reins that are attached to the bit. It provides additional control and communication through rein pressure.
A hunt seat style English bridle
Western show bridle
The crownpiece runs over the horse's poll, and the browband across the forehead. The cheekpieces run down the sides of the horse's face.
A double bridle, using two bits