• Fits E-sync hubs and includes pawls, springs, pawl retainer, 0.5mm freehub spacer, 1.8mm cassette spacer, and freehub seal. Bearings are pre-installed. • Compatible with SRAM XDR style cassettes. • SRAM XD cassettes are compatible when used in conjunction with the included spacer. • Not compatible with any Shimano cassettes. • Also compatible with Neo and Neo Ultimate hubs as a more durable upgrade. • Replaces ZH1642