The Chris King Thru Axle ISO XD Boost Rear 12x148mm Disc Hub brings Boost axle width compatibility to your favorite SRAM XD cassette and shiny new, Boost equipped whip. Compared to its narrower siblings, the Boost ISO features a slightly tweaked shell shape 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 Thru Axle ISO XD Boost Rear 12x148mm Disc Hub utilizes Chris King's Ring Drive freehub system for lightning fast engagement and that signature swarm of bees sound when coasting. It's available with your choice of 28 or 32 holes.