Shimano slx hg81 10sp cassette chain bundleshimano drilled lightweight 10 speed cassette designed for super narrow 10 speed hg chains featureshg81 10 speed cassette featuring light weight minimal design sprocket carrier4 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