Zipp Spare - Wheel Freehub Kit 176/177 12 Speed Sram - Xdr:

The XDR™ driver body is a universal mounting system for cassettes that incorporate cogs with fewer than 11 teeth. It allows for lighter and more versatile drivetrains without requiring new rear axle standards, cassette tools or hub redesigns. The XDR™ interface is 1.85mm longer than XD™ and is designed for road hub applications. XDR™ driver bodies are compatible with all XD™ cassettes when the cassette is installed with a 1.85mm spacer.

SPECIFICATIONS
Driver body type: SRAM XDR
Axle type: QR/Thru Axle
Speed (Hub - Drivers): 11,12