Merritt used a traditional clutch style system paired with our 9T Diamond Driver (the driver comes with a lifetime guarantee). There driver replaces the small bearings, the most common source of failure in freecoasters, with polymer bushings along its entire length. The hub shell is super slim & CNC’d 6061 aluminum with a hollow chromoly axle. The hub comes set with maximum slack but adjustment washers are included to reduce slack if desired. section Product Specs HUB TYPE: Freecoaster AXLE: 14mm Male DRIVER: 9t SPOKE HOLES: 36h WEIGHT: 564g / 19.9oz