The workhorse of the X-Range gearbox. The Sram Red XG-1290 cassette runs smoothly and quickly through a wider gearbox. It is specifically designed for wireless electronic shifting and the one-piece design gives you the best weight savings. Updated design for smoother and faster shifting. A more gradual progression of gears between cogs - at least five single-tooth jumps - still provides greater range. The 10-tooth start provides a larger gear range. Designed to work with an XDR driver body. One-piece X-Dome design made from machined steel for weight savings. All Zipp wheels from 2012 onwards are XDR -ready.