Sram XG-1251 XPLR XDR 12 Speed Cassette 10-44tThe Sram XG-1251 XPLR XDR 12 Speed Cassette has X-Range gearing for a massive 440% range to provide smooth gear progression when you’re sweating up gravel climbs, and tight jumps on the high end for when it’s time to drill it on asphalt. Shift features on each cog are optimized for electronic shifting, so you’ll get fast, smooth and precise shifts every time. The Mini Cluster hybrid cassette construction combines four small cogs are CNC Machined out of a single block of billet steel with an additional eight cogs that are individually pinned together. The XDR driver bod is a universal mounting system for cassettes that incorporates cog with fewer than 11 teeth. XDR driver bodies are compatible with all XD cassettes with a 1.85mm spacer. These cassettes have 10-11-13-15-17-19-21-24-28-32-38-44t. Compatible with Flattop chains.710845869006