This 5DEV spider allows the integration of Shimano Dura-Ace 12-speed rings with their RGXC 8-Bolt crank interface. The asymmetric 110 BCD 4-Bolt chainring bolt pattern works exclusively with Dura-Ace 2x chainrings. Please note that this chainring is not compatible with Ultegra or GRX chainrings.Allows the integration of Shimano Dura-Ace 12-speed rings with the 5DEV RGXC 8-Bolt crank interfaceCNC'd machined aluminum is lightweight at only 73g Please note - If you want to run Shimano 11-speed Dura-Ace you'll going to need to use a FC-R9200 12-Speed small ring otherwise you'll run into compatibility issues