Genuine Shimano replacement part 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 lightweight alloy carriers to reduce weight and increase rigidity Sprockets are cut away and drilled to further reduce weight without reducing rigidity Light and durable 40/42T sprockets Chrome-plated finish offers hard wearing resistance to corrosion Alloy cassette lockring For 11-speed HG-X11 MTB chains .