These Shimano GRX RX820-2 anodized aluminum chainrings are for specifically designed for use with GRX FC-RX820-2 2x 12-speed cranksets. Aluminum 48t outer chainring is lightweight and features a hard anodized finish for added durability 4-Bolt Asymmetric 110 BCD Designed for use with 31t inner chainring (sold separately) Specifications Ring Position/Type Outer Tooth Count 48 Drivetrain Speeds 12 Round or Oval Round Chainring BCD 110 Shimano Asymmetric Material Aluminum Color Black Weight 102 Defined Color Black Number of Bolt Holes 4-Bolt