External BSA, English threaded bottom brackets featuring a unique self-cleaning hybrid ceramic bearing system for the ultimate in strength and durability Cartridge bearing system features a single ceramic ball with the remainder being steel with steel races, combining the strength of steel and the bearing life of ceramic Single ceramic ball bearing pulverizes contaminates, reworks and polishes the steel races with every rotation Offered in 24mm (Shimano, FSA, Race Face, etc) with an expandable sleeve that fits 68mm to 100mm shells Bearings include a 5 year warranty