Hg81 10 speed dyna sys cassette featuring light weight minimal design sprocket carrier the 3 largest sprockets are mounted on a lightweight alloy carrier to reduce weight and increase rigidity 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 rigidi