Black Diamond hubs are the true pinnacle of modern engineering and cnc capabilities ABEC 5 Enduro 2RS cartridge bearings with graphite retainer cages for durability, 2 in front hubs, 4 in rear Hardened, rust proof steel construction for extreme longevity and cassette dig-in prevention Two powerful, circular magnets to push two ratchets together - no springs, no pawls Magnetic ratchets resist corrosion from mud, water and debris External bearing preload nut in both hubs will keep bearings in optimal condition RR 8-11s Cass 32H 12TA Aly Blk 268g 6B 142mm 55.5mm 55.5mm 34mm 20mm