8″ Shank. 1 3/8″ Polo Port with Copper Cover. This line is what started the company and has proven over the past 5 decades to be of great design and craftsmanship. All these bits feature the square pin loose jaw, which eliminates the cheeks from turning, yet allowing the action required in a loose jawed bit. This line is the heaviest we offer, which aids in steadying a horse’s head.