Shimano FC-7900 Dura-Ace 42T Chainring - 42T-AShimano FC 7900 Dura Ace 42T Chainring The Shimano Dura Ace FC 7900 10 speed chainring stands for a precise, clean shifting function that is made possible by the SG X technology. All versions are made of aluminium, the large chainrings are also hollowed (Hollowglide). Numerous possible combinations and perfect interaction with other components (HyperDrive System) are guaranteed. This chainring can only be used with Shimano Dura Ace FC 7900 10 speed