There are times when the simplest solution is the best one. In the case of the new OG 1090 Cassette, simplicity also means elegance, efficiency, and performance. We took up the challenge of re-engineering the cassette from a component made up of many parts down to strippeddown but exceptionally strong set of cogs that stick firmly to SRAM Red's core principles of light weight, higher efficiency, and maximized technologies. Lightweight: Innovative CNC'd chromoly steel construction. Durable: 35% harder than titanium! Capped with a premium electroless nickel finish. Stiff: 15% stronger that its nearest competitor due to the one piece construction. OpenGlide technology allows for the smoother transition between gears when up- and downshifting. OG 1090 design merges stiffness, durability, and simplicity in a revolutionary new package. Speeds:10. Recommended Chain: PC 1090R, PC 1090, PC 1070. Lock Ring Material: Aluminum Anodized. Sprocket Material: Heat-Treated Steel.