The leader of a team of horses like the 'Attelages du Val d'Amour' acts on the horses through the reins extended by the mouth of the bit, the only direct link with the horse. The bit has an impact on the spinal rod of the horse by the effect of the reins, the lower jaw of the horse on which it rests being connected to the skull of the animal by the two temporomaxillary joints. The bit is considered to be correctly placed when the corners of the horse's lips are approximately one centimeter above the middle of the space between the hooks and the molars.