Convert your ISO B and Boost 6-Bolt hubs to fit Shimano HG, Micro Spline, or SRAM XD cassettes using our latest technology. Gen 4 conversion kits include a pre-assembled axle, driveshell, and adjusting clamp for a plug and play swap. Installation requires a 2.5mm hex key and T10 Torx tool. Twin bearing Stainless steel bearings. Latest Gen4 Internals Suits 148mm Boost hubs only Compatible with ISO B 6-Bolt hubs. Serial numbers will begin with 851.