SRAM Red OG 1090 Cassettes 2010. Sometimes the simplest solution is the best one. In the case of the OG 1090 Cassette, simplicity also means elegance, efficiency, and performance. The main cog set 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. The sprockets have all been designed with SRAM 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 steels superior strength and stiffness. Lightweight, innovative CNC chromoly steel construction. Durable 35% harder than titanium! Stiff: 15% stronger than its competitor. OpenGlide technology allows for smoother transition between gears.