The Wolf Tooth Dura-Ace R9200 Aero Chainring converts a Shimano Dura-Ace R9200 crank to 1x without giving up the range a 2x setup provides, pairing with a wide-range cassette to cover similar ground. It's built specifically for the R9200 crank and won't fit Ultegra, 105, or any 2x drivetrain, so the fit is exact rather than approximate. What Our Gearhead(R) Experts Are Saying:"I hit a rough, punchy gravel section standing out of the saddle and the chain never skipped or threatened to drop off the Drop-Stop teeth. That's the kind of retention that lets me run 1x on Dura-Ace without carrying the anxiety of a dropped chain mid-ride."