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 - Hollowglide technology provides high rigidity and cuts down on weight while maintaining strength - Offers better power transfer and quicker, more precise front shifting - 50t outer chainring is for use with 34t inner chainring - 54t outer chainring is for use with 40t inner chainring