AB Premium Shimano 110/4 bcd compatible oval chainrings are designed for new type of Shimano cranks Dura-Ace 9100 & Ultegra 8000. Compatible with Di2 These are finest oval chainrings on the market in terms of shifting, smoothness of pedaling and manufacturing quality. Same esthetically as older model. IMPORTANT: These chainrings are also Backwards compatible for 9000, 6800. Mounting tabs are a little different in appearance from older model, but with use of dedicated 9000 or 6800 Bolt covers they look perfect. This is especially important for 53/39 combination as we only provide it under this category but can be retrofitted to 9000 and 6800 cranks.