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. Hollowglide technology provides high rigidity and cuts down on weight while maintaining strength. Offers better power transfer and quicker, more precise front shifting. 54t outer chainring is for use with 40t inner chainring. Asymmetric 110 BCD. Compatible with HG 12-speed chains. Item Specifications: Color: Black, Ring Position/Type: Outer, Tooth Count: 54, Round or Oval: Round, Drivetrain Speeds: 12, Chainring BCD: 110 Asymmetric, Material: Aluminum, Defined Color: Black,