Machined aluminum shell threads together for precise bearing alignment and frame fit, reducing bottom bracket creaking and premature bearing wear. Features: Replaceable Enduro bearings Made in the USA ZER Ceramic sealed bearings Oversized Grade 3 balls roll on races which are ground to a mirror finish after receiving Magnetite and then Cryogenic treatments for hardness and longevity Silicone VV-type 2-lip non-contact labyrinth seals for excellent bearing protection with minimum friction Long-lasting Rheolube synthetic grease helps prevent contamination Nylon/graphite retainer to further minimize friction Specifications: Frame Interface: BB30 Spindle Interface: 24mm (Shimano Hollowtech II, FSA MegaExo, FSA MegaExo Light, RaceFace EXI) Bottom Bracket Shell ID: PF42 Shell Width: 68mm, 73mm Material: Ceramic Bearings, Aluminum Shell Color: Black Weight: 127g