7075 T-6 aluminum cups Compatible with tapered 1-1/8` to 1-1/2` steerer tubes, or straight 1-1/8` steerers with a conversion crown race (sold separately) Aluminum dual seal crown race protects lower bearing Carbon-friendy compression ring captured in top cover Stainless bearings feature Split-Lip seals for twice the protection of a typical cartridge bearing ZS44/28.6|ZS56/40 Black 28.6 44 40 12 - 1-1/8 to 1.5`