Do you need a spacer on the XDR driver body when fitting a cassette?

For SRAM Eagle 12-speed 10-50T, Eagle 10-52T cassettes, or 11-speed 10-42T cassettes, you will need to install a 1.85mm spacer on the driver body before installing the cassette. For SRAM 12-speed road cassettes, no spacer is required. The 1.85mm spacer is included with XDR driver equipped wheels, like the Zipp 101 XPLR.