Freehubs (drivers) are hub-model and drivetrain specific. If you don’t already know your hub model, enter your wheel’s serial number, located on the outside of the rim, into the search field at the SRAM Service Hub:
It will bring you to a list of key features of your wheel, including the hub type:
Ask your dealer to order the freehub for the hub model specified. Links to other helpful service documents, including the Wheel User Manual and Hub Service Manuals, are below the Wheel Specifications. If you would like to find more detailed information, including ZIPP service part numbers and wheel exploded views, find your wheel in the ZIPP Spare Parts Catalog.