This derailleur is designed for Shimano GRX cranks. Features our patented Drop-Stop® design for improved wear resistance and chain retention. The newly updated tooth profile works with the SRAM Flattop chain and other 9, 10, 11 and 12 spd chains (except the Shimano HG+ 12 speed chain). Compatible with Shimano GRX cranks including RX600 and RX810 The Drop-Stop B tooth profile is compatible with SRAM Flattop chains Wolf Tooth's patented wide/narrow Drop-Stop tooth profile provides maximum chain retention and mud shedding capability Use Drop-Stop B for all 9, 10 and 11spd chains or 12spd SRAM Eagle, SRAM Flattop, Campagnolo, KMC, Connex or Wippermann chains Weight: 36t - 65.5g | 38t - 72g | 40t - 84g | 42t - 89g | 44t - 92g | 46t - 102g Material: 7075-T6 aluminum Chainline: 50mm (same as Shimano GRX chainrings) Made in the USA