Stan's Freehub Bodies and Parts. Features: Replacement freehub bodies include pawls and springs pre-installed M-Pulse hubs: six pawls are equipped with Neodymium magnets engaging every 1.66 deg E-Sync hubs: fast 8.18 deg engagement with reinforced high-torque pawls HG 11sp road FH body requires a 1.8mm spacer (included) for use with a Shimano/SRAM 8-11sp HG mountain cassettes XDR drivers require a 1.8mm spacer (included) for use with a XD cassette Instructions and hub axle determinations are available online @ www.notubes.com Specs: Description:MicroSpline 12sp FH body Compatible With:M-Pulse hubs