Dura-Ace 10-speed cassette Super lightweight 10-speed cassette with a rigid alloy carrier for excellent shifting even under the most demanding gear changes Hyperglide sprockets have a computer designed tooth configuration with contoured shift gates, resulting in a crisp smooth shift even under load Close ratio gearing allows a more efficient use of energy through finer cadence control Largest sprockets are mounted on a lightweight alloy carrier to reduce weight & increase rigidity