The Kogel T47 External Bottom Bracket is one of the smoothest and most reliable options on the market. Featuring ceramic bearings, this bottom bracket is made to run like new for years on end while enhancing your power transfer. This version is designed to accommodate 24mm Shimano, Rotor, and SRAM GXP cranks. A 12-notch bottom bracket tool with a 44mm inner diameter like the Park Tool BBT-79 is all you need to install it. These strong seals are designed for MTB and gravel riders to keep moisture and debris out. Kogel knows that every pedal stroke is important, and hand makes their bottom brackets to maximize your efficiency.