Replacement freehub bodies include pawls and springs pre-installed MK3, Comp, & Team wheels all have Durasync freehub bodies. Pro wheels feature the Speedsync freehub bodies Speedsync freehubs offer 6-pawl, 5 degrees, double engagement with 3 stainless bearings for axle stability Speedsync freehubs offer 6-pawl, 5 degrees, double engagement with 3 stainless bearings for axle stability Durasync S freehubs offer simultaneous 6-pawl, 10 degrees, engagement with 3 stainless steel bearings for axle stability Durasync freehubs offer simultaneous 6-pawl, 10 degrees, engagement with 3 bearings for axle stability