Get your mountain bike running smoothly with Industry Nine's Hydra Complete Freehub Kit which allows you to replace your current freehub with ease. This kit has everything you need to make the replacement process quick and straightforward, so you can spend more time enjoying your ride! Note that if you're converting from Shimano Micro Spline, you'll need to use either HAX2631 (QR) or HAX2637 (12x), as per the factory spec. Compatible With Hydra Generation 1 mountain rear hub shells.