The Shimano Dura-Ace 9000 Chainring fits the new 9000 series Dura-Ace crankset which utilizes a 4 arm x-shaped spider and a 110 bolt circle diameter. Shimano makes the 5th arm disappear, shaving some weight, yet still produced the stiffest ring to date. The gain in stiffness comes from Shimano’s Hollowglide Technology and integrated chainring nuts make replacement a very simple task. Chainrings are designed to work together as a set. For crisp and accurate shifting, ensure you are purchasing the correct ring to match your specific tooth count.