Correction Port D-Ring Bit.The Low Port Correction D Ring is a super nice bit for horses at the intermediate level of their training program. The joint on each side of the port allows each side of the bit to work independently. The hooks on the D Rings offer various leverage options. Pressure is applied to the palate and bars. Copper inlay on the mouth promotes salivation and increases sensitivity. Stainless Copper Inlay Rings: 3 Mouthpiece: 5 Port Height: 1 Bit diameter: 10mm