The shimano hg81 slx 10 speed cassette is a 10 speed dyna system cassette featuring a 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 for a more efficient use of energy through finer cadence control the sprockets are cut a