The BSA, or English threaded, bottom bracket is a traditional shell size. It has an inner diameter of 34mm and is 68mm wide. These cups thread into the BSA shell making it possible to install SRAM and Quark 24/22mm spindle cranks. The Ceramic Speed kit comes with bearings pressed into threaded cups, which are then threaded into the frame. Those bearings consist of either Ceramic Speed Standard or Coated Bearings. Super smooth, super round Ceramic Speed balls are rotating in hardened-steel races in both. The Coated version has a metallic coating laid onto the races, making it even smoother and harder, resulting in longer life and lower drag.