Dura-Ace FC-R9200 chainrings are constructed with high quality aluminum and are compatible with FC-R9200 and FC-9200-P 2x 12-speed cranksets. Aluminum with anodized finish provides durability and light weight. 40t inner chainring is for use with 54t outer chainring. Asymmetric 110 BCD. Compatible with HG 12-speed chains. Item Specifications: Color: Black, Ring Position/Type: Inner, Tooth Count: 40, Round or Oval: Round, Drivetrain Speeds: 12, Chainring BCD: 110 Asymmetric, Material: Aluminum, Defined Color: Black,