With the shifting trends toward wider tires and boost axle widths, Chris King offers its venerable ISO hub in 12x148mm spacing, along with the XD drive shell and the HG Shimano/SRAM drive shell. The Chris King ISO B Boost Rear Hub features a slightly tweaked shell shape compared to its narrower siblings and thickened flanges for increased strength. Long known as a versatile hub built to tackle a wide range of terrain, the ISO adds strength and stiffness for precise tracking and confident handling over technical trails. The Chris King ISO B Boost Rear Hub utilizes Chris King's Ring Drive freehub system for lightning fast engagement and that signature buzzing swarm of bees sounds when coasting. It's available with your choice of 28 or 32 holes.