The PF4130 bottom bracket is Press Fit into 41mm diameter shells that are 86. 5mm wide and mate most cranks with a 30mm spindle to that standard. If you have a BB86 frame and want to install a 386EVO crank or Rotor 30mm crank, this is the kit you need. CeramicSpeed bearings are installed in cups. The Standard Bearing has ceramic CS balls and hardened-steel races. The Coated Bearing has the same balls running on hardened-steel races with a 3-micron thick metallic coating making the races harder and smoother, increasing service life and reducing friction.