High tolerance cold forged aluminium link plates and body construction provide for extremely light weight, strength and durability. High rigidity wide outer link plates the pulley body to increase pivot joint rigidity. Sealed pulley bearings reduce friction and rotate silky smooth increasing efficiently. Four self-lubricating micro-machined fluorine-coated link pivot bushings provide low-friction shifting. Pulleys are made of tough DuPont Zytel for longer life and less chain noise. With a total capacity of 33 tooth, it is able to operate with wide gear ratios up to a 28 tooth cassette sprocket. Hard wearing Dura-Ace finish and graphics for long lasting good looks. 10-speed compatible. Dura-Ace rear derailleur with lightweight carbon cage and wide link design gives quick accurate shifts, and unmatched drivetrain efficiency. Full carbon fibre inner and outer pulley plates enhance rigidity and significantly reduce weight.