Industry Nine Hydra 2- Superboost 6 Bolt Hub - RearCompletely re engineered using insights gleaned from more than 100,000 original Hydra hubs in the field, Hydra2 features a newly designed 65% thicker axle, larger 6903 bearings with new labyrinth seals, and enlarged pawl pockets that ensure bombproof durability under the most demanding conditions. If that wasnt enough, a refined drive ring and an extra tooth on each pawl enable Hydra2 to deliver lightning fast 0. 41 engagement with less coasting drag