The XX1 group fulfilled a lot of weight loss resolutions when it initially dropped, shaving up to half a pound off of some machines. But it did come with a cost: a new driver to grant more clearance for the eleventh cog. There was a corresponding rush by wheel manufacturers to get on board the XX1 train, and the venerable experts at Reynolds were no exception. The result is the Reynolds XX1 Freehub Body. Reynolds changed up its freehub design for 2014, so you'll need to figure out which hub style you have to ensure you get the correct part. The 2013 style is listed as the Pawl style, while the 2014 and later version is listed as the Ratchet style. A quick way to tell the difference is that the 2014 hubs have a serial number behind the drive side flange. But to be sure, it's best to remove the freehub, and check the location of the pawls. On the 2013 freehub, the pawls are located in the freehub. On the 2014 version, the pawls are located inside the hubshell, so they'll stay put when you pull the freehub. The Reynolds XD Driver is available in two sizes, one for the 2013 style, listed as the Pawl hub, in the color Red, and one for the 2014 style, listed as the Ratchet hub. End caps are included. Please note that the XD Driver is for use only with SRAM's XX1 and X01 drivetrains.