Shimano 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. Asymmetric 110 BCD Compatible with HG 12-speed chains Aluminum with anodized finish provides durability and light weight 40t inner chainring is for use with 54t outer chainring Specifications Color Black Ring Position/Type Inner Tooth Count 40 Round or Oval Round Drivetrain Speeds 12 Chainring BCD 110 Shimano Asymmetric Material Aluminum Defined Color Black