Freehub bodies for Zipp Cognition hubs.1.8 mm spacer is included for use with XD cassettesFor Gen 2 Cognition hubs manufactured after the 21st week of 2018 (serial number would be 21P8 or higher, such as 51P8)Gen 2 hubs feature a one-piece axle systemEnd caps sold separatelyItem SpecificationsCassette Body TypeSRAM XDCassette Body TypeSRAM XDRMaterialAluminum Zipp Cognition Freehub Freehub Body UPC: 710845808340