Compatible with Shimano and SRAM freehub. High quality aluminium spacer, to fit an 8, 9 or 10 speed cassette on an 11 speed freehub. Fits: Shimano or SRAM 11 speed freehub, 8, 9 or 10 speed cassette. This spacer is necessary if you need to fit an 8-10sp cassette onto an 11sp hub.