Brand New 32 Hole 6 Bolt XD Freehub Boost This is a set of DT Swiss 350 hubs, specifically designed for mountain bikes. The front hub has a 15x110 interface and the rear hub has a 12x148 interface, both with a 6-bolt pattern. The hubs are made of aluminum and include a 36T ratchet. They are also compatible with XD hubs.