Hg81 10 speed dyna sys cassette featuring light weight minimal design sprocket carrierthe 3 largest sprockets are mounted on a lightweight alloy carrier to reduce weight and increase rigidityhyperglide sprockets have a computer designed tooth configuration with contoured shift gates resulting in a crisp smooth shift even under loadclose ratio gearing allows a more efficient use of energy through finer cadence controlsprockets are cut away and drilled to reduce weight without reducing rigidityfor