SRAM X.O Rear Derailleur - Medium Cage

"The top-of-the-line SRAM rear derailleur is the perfect upgrade for your SRAM equipped bike. Forged alloy links and B-knuckle, High Strength Grilon P-knuckle, Machined and heat treated oversized pivot pins, sealed cartridge bearing pulleys, carbon cage; all for lightweight durability. 1:1 actuation ratio and direct route technology creates lighter effort precise shifting. 8/9 speed."