This freehub makes your 20181 Wahoo KICKR and KICKR CORE indoor trainer compatible with Campagnolo 10,11 and 12 speed cassettes. It will ONLY work with these editions of the KICKR and CORE and is not compatible with any of the older editions. The updated freehub design also allows a user to easily switch between a Shimano/SRAM cassette and a Campy cassette. The freehub body comes with 11T and 12T lockrings to match the installed cassette.