High quality 9-speed cassette 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 Sprockets are cut away and drilled to reduce weight without reducing rigidity Nickel-plated finish offers hard wearing resistance to corrosion Corrosion-resistant steel cassette lockring For Super Narrow 9-speed HG chains Average weight 270 grams for 12 - 23T