When building a wheelset for our mountain bike, the Industry Nine Hydra MTN Classic Boost Hubset is one of our top choices for performance on the trails. Featuring a precision-built design, quality aluminum construction, and an aggressive 690 points of engagement, the Hydra MTN Classic Boost Hubset is the cream of the crop when it comes to high-performing mountain hubs. This set includes the front and rear hubs and is available in 32 or 28-hole configurations.