Trek developed their own bb standard to optimise their frame designs. BB90 has a 90.5mm shell width and 37mm inner diameter and is designed so that the bearings of external cups can hide within the frame. The CeramicSpeed kit comes as two bearings, which are then pressed into the frame. Those two bearings consist of either CeramicSpeed Standard or Coated Bearings. Both feature super smooth, super round CeramicSpeed balls rotating in hardened-steel races. The Coated version has a metallic coating laid onto the races, making it even smoother and harder, resulting in longer life and lower drag. In The Box 2 bearings. 2 dust covers. GXP wave washer. Plastic cable protector. 10ml syringe of CeramicSpeed All Round Grease. Sticker sheet.