These chainrings from KMC are suitable for Bosch 4th generation motors. Guaranteed to last a minimum of 3500km, combining these with KMC's E chains to extend the life of your chain and chainring even further. Longer lasting, quality material and unparalleled gear changes.**Features*** Perfectly tailored to narrow KMC chains * Hardened CrNo steel * High efficiency, saves battery * Extreme durability, highest precision* Simple conversion* Perfectly matched with KMC Chains**Tech Specs*** Size: 1/2" X 11/128"* Colour: Black* Treatment: Hardened Chromoly steel* For Bosch 4 systems* Direct mount: 9mm offset* E1, E12, E11, E10, E9 & E8 chains