Trek developed its own standard for cranksets to optimize frame designs. The BB90 has a bottom bracket width of 90.5 mm and an inner diameter of 37 mm and is designed so that the external bearing cups can be hidden inside the frame. The CeramicSpeed kit consists of two bearings, which are then pressed into the frame. These two bearings are made of CeramicSpeed Standard or Coated Bearings. Both feature super smooth and super round CeramicSpeed balls that rotate on hardened steel races. The Coated version has a metallic coating applied to the races, making it even smoother and harder, resulting in greater durability and less friction. In the package: 1 24 mm BB90 bearing 1 22 mm BB90 bearing for GXP 2 seals 1 24 mm integrated dust cover 1 metal dust cover for GXP Wave washer + spacers Universal grease Decal