The 7 shank helps activate the bit before the hand. Good for Western Pleasure and other Western Performance events.
Usage:
With pressure on both reigns, uses pinch and restrict with a release,restricts the tongue and collapses on the bars.  Pressure is dispersed across wide center barrel as it rolls down into the tongue.  To allow a rider to lift one side off the tongue to the bar, each side of the mouthpiece moves independently.  Roller appease busy-mouthed horses.