SRAM has forever changed how we ride, and shift our mountain bikes by reducing the number of front chainrings to just one and designing their 11-speed cassette with a 10 tooth high gear. On the low-end is an impressive 42 tooth cog for a very wide range of gearing. This larger cog is made from aluminum to save weight while the rest of the cassette is machined from steel for improved strength and no-flexing under load. Please remember that this unique cassette is specifically designed for use within a complete SRAM 11-speed one-by drivetrain and requires a rear wheel equipped with an XD Driver freehub body. Add gears to your SRAM one-by equipped mountain bike without adding weight with a XG-1199 XX1 cassette.