The revolutionary machined design of the XX Cassette uses the same grueling manufacturing techniques that produced the PowerDome? road cassette. With X-DOME?, eight of the cogs are CNC machined together out of a single block of billet steel, creating an incredibly lightweight, precise and strong cassette. it´s a process that takes nine hours per cassette. You have never seen a cassette that looks like this. The open design aids in mud clearance, giving you cleaner shifting performance and longer component life.