These cassettes are made from two solid pieces of 7075 aluminum alloy.  These are machined using a computer numerically controlled (CNC) mill into an amazing example of industrial artistry.  The 12-23t saves you just over 50 grams when compared to a Dura-Ace cassette of the same size.  In order to provide maximum durability, the exterior of the cassettes is shot-peened.  This involves blasting the outside with tiny ceramic balls to surface harden the metal.  Finally, a hard ceramic oxide coating is anodized onto the cassette.  These steps reduce the rate of abrasive wear, but an aluminum cassette is still definitely a "race day" component.


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Typical lifespan is 1000 - 2000 miles, but obviously this will vary depending on the gearing you use and your riding conditions.  Note that "big ring" riders will typically see longer life spans.  The higher torque pressure created by small ring gearing is more likely to cause gradual deformation of the cassette teeth.  These are a good card to play when the seconds really count.  Please note that the weights below all INCLUDE the supplied lockring.  Somehow, a lot of manufacturers seem to "forget" to include all the necessary parts in their published product weights!  Please keep this in mind when comparison shopping.