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 away and drilled to reduce weight without reducing rigidity. Designed for 10 speed HG-X MTB chains.