Shimano's SLX Dyna-Sys 10-Speed Cassette features chrome-plated steel sprockets mounted to an aluminum carrier for an ideal blend of durability and low weight. Closer gear ratios in the middle of the cassette ensure you'll have the perfect gear for the trail's ups and downs. Plus, the cogs are ramped and machined for flawless shifts with the 10-speed chain and Shadow rear derailleur (both sold separately).