Prestacycle UniBlock PRO Cassettes are machined from a single solid block of cold-forged Chrome Molybdenum alloy steel, then heat-treated, tumble-finished and electroplated for added durability, low-friction operation and longer service life. The UniBlock PRO cassettes feature ARC(TM) shifting tooth profile technology that provides the fastest, smoothest possible shifting to all systems while minimizing the impact to power delivery. - Single block design offers 3D structure to optimize strength and distributes forces that allows Prestacycle to remove more unnecessary material making the ultra-light - Single block design ensures more freehub engagement by reducing torsional loads for less freehub wear and insuring the lowest rolling resistance within the freehub - ARC(TM) (Advanced Radial Curve(TM)) Shifting Technology optimizes every single tooth pairing for exact-match pairings for both up-and-down shifts provide the highest possible speed and reliability in shifting... Even shifting under load is maximized - Compatible with all Campagnolo 9-12 speed freehubs, as well as N3W adapter kit - Wider inner and outer freehub teeth maintain engagement at all points in all gears and create an overall increase in freehub contact, no matter what gear you are in - Includes red anodized locknut