Due to the specific shape of the rings (D-rings) the rider has more influence from outside on the horse’s mouth. The lateral guiding provides for a more stable position of the bit and prevents the bit from being pulled through the horse’s mouth. The D-ring prevents jamming between the muzzle and the ring and thus prevents the lips and the corners of the mouth from getting hurt.
Copper on the bit promotes better acceptance because it encourages the horse to chew, thus enhancing the saliva production.
Have your horse feel no pressure on the palate with the double broken bit. Balanced weight distribution on tongue and jaw so the horse can easily be ridden on the bit. No nutcracker-effect and more forgiving to mistakes caused by a rider’s strong hand or pulling on the reins