This is a specialty piece of equipment at is truly unique. Its function is to exert pressure on the jaw of horses who have a tendency to severely gap open and be strong in the hand. It is several steps up from a crank noseband.
It is sweet iron so it is not visible while riding. Standard is 7/8″ wide with 7/8″ loop on one end and an open loop on the other. It is designed to attach underneath a standard noseband on the jaw/buckle side.