This is the Sram Red® XG-1290 cassette. This cassette uses X-Range™ technology to meet the modern demands of road cyclist. Starting with a 10-tooth cog in the back, this 12-speed cassette offers a greater gear range. To help you find the perfect cadence, each XG-1290 cassette consists of at least 5 one-tooth jumps. The one-piece X-Dome™ design makes a lightweight and strong cassette with great mud clearance.