CEMA MacBook Pro Unisex Adult Watch XL Black

CEMA MacBook Pro Unisex Adult Watch XL BlackInterlock design to reduce noise issues & give Excellent rigidity.24mm or 30 mm Bearing ID Design to fully transfer pedalling power from axle.Active seals to easily maintain bearings & add grease.Double O-ring design to prevent water entering frame & as buffer between frame and BB.Compatible with Shimano and SRAM system by assembly parts.Easily tighten up with locking kits.