We took the standard cassette and turned it inside out! The main cogset of the OG-1090 cassette is machined out of a single forged form that is heat treated and then shaped in a complex series of CNC-guided operations never before seen in this type of application. This is truly a revolutionary design that will take you by surprise with its ingenious simplicity. The sprockets themselves (including two free cogs) have all been designed with SRAM's proprietary OpenGlide design for smooth-as-silk up- and downshifts. Weight, stiffness, and strength-wise, the radical OG-1090 cassette delivers titanium's desirable weight, with solid steel's superior strength and stiffness.