Shimano Dura-Ace RD-R9250 Di2 Rear Derailleur Next generation shifting The new Dura-Ace RD-R9250 derailleur is the best way to experience Shimano's latest and greatest 12-speed Di2 platform. It delivers Shimano's fastest ever shifting with the new derailleur being a whopping 58% faster than the previous generation 11-speed Di2 derailleur. Its sleek and compact design has been refined while the cassette capacity can now support upt an 34t cassette. Straightforward charging and wireless connectivity make the install and setup process super easy. Being the Dura-Ace level derailleur this is the lightest possible derailleur available for your 12-speed Shimano road setup. So if you're looking to shave off as many grams as possible then this is the way to go. Features Shimano's fastest ever shifting with the new derailleur being 58% faster than the previous generation Wide range cassette support up to a 34t cassette Sleek and compact design looks fantastic Straightforward charging and wireless connectivity keeps the setup simple Drivetrain speed: 12Drivetrain Compatibility: 12-speed Shimano Road Di2Weight: 215g | Shimano | Dura-Ace Rd-R9250 Di2 Rear Derailleur 12-Speed, Medium Cage, Black