English threaded bottom brackets are known as BSA; it stands for British Standard Cycle. English threading for MTB means a 73mm wide shell, with an internal diameter of 34mm and reverse threading on the drive side. It is the most common threaded standard used today. This kit works with cranks with a 24mm diameter spindle, found on Shimano, FSA, Rotor, among others. The cups have pre-installed CeramicSpeed bearings. The Coated Bearing features CeramicSpeed balls that rotate on a 3-micron thick coating applied to the hardened steel races for increased durability and less friction. In the box: 2 threaded cups with bearings 2 dust covers with integrated spacers Spacer tube Long Life Grease Decal