Same chain retention, less noise and cleaner performance! NEW removed ridges so it is easier to keep the ring looking clean NEW tooth profile to run quieter, and cleaner Narrow Wide tooth profiling ensures ultimate chain retention Stiff 4mm plate thickness transfer loads without flexing 7075-T6 aluminum, aerospace grade strength Laser etched graphics Compatible with 9, 10, 11 and 12 speed ArmxBCD: 4x104 4-bolt