Shimano deore m615 10 speed double chainsetgreat value deore 2 piece design chainset for 10 speed dyna sys mtb hg x transmissions intuitive dyna sys gear combination bring rider bike and trail together rider tuned fit various bike and riding style by choice of gear combination features the 2 piece design chainset features an external bottom bracket system which is a lightweight rigid design that is incredibly strong and durable lightweight and rigid steel bottom bracket axle sg x chainrin