Precision bored fully concentric bearing seats for a smoother spin and prolonged bearing life Precision bored fully concentric bearing seats for a smoother spin and prolonged bearing life 20mm 7075-T6 aluminum axle with steel helicoil thread inserts 3/8` heat-treated chromoly axle bolts with 17mm wrench flats and a 6mm hex slot 2 composite hub guards included 6804RS sealed cartridge ball bearings 7075-T6 aluminum hub shell