The Wolf Tooth Direct Mount Chainrings for Bosch E-Bike Motors are compatible with all Boost and Super Boost bikes that use the Bosch Gen 4 E-Bike Motor. This continues the Wolf Tooth product line of Drop-Stop chainrings for e-bike motors. Direct Mount Chainrings for Bosch E-Bike Motors are machined with 7075-T6 aluminum at Wolf Tooth in Minnesota, USA. Compatibility - Chainring is compatible with all Boost and Super Boost bikes that use the Bosch Gen 4 e-bike motor - Drop-Stop B tooth profile is compatible with almost all 9-, 10-, 11-, and 12-speed chains, including SRAM Transmission T-Type - Drop-Stop ST tooth profile is compatible with Shimano HG+ 12-speed chains and KMC 12-speed chains. - 55mm chainline - Available in two different tooth profiles for optimal performance based on your chain type. Use Drop-Stop ST for use with Shimano 12-speed Hyperglide+ and 12spd KMC chains. Use Drop-Stop B for all 9, 10, and 11spd chains or 12spd SRAM Eagle, SRAM Flattop Road or Transmission (T-Type), KMC, Connex or Wippermann chains.