The professional's choice.Experience SRAMR X.0 the pro ready rear derailleur that's lighter, stiffer, smoother and flat out better looking than anything out there. With a potent mix of high grade metals forged aluminum and titanium reinforced carbon composite, advanced engineering and smart design, SRAMR X.0 is the ideal upgrade for your current SRAMR system. Technology:: 1:1R Actuation Ratio SRS technology for light, precise indexing. Speeds:: 89. Indicator:: Quick View. Body:: 50mm Shorty w lightweight GrilonR, carbon finish and ergo tornado style grip. Compatibility:: SRAM 1:1 rear derailleurs, SRAM or ShimanoR front deraillersOther:: Teflon coated cables w tethered never lose port cover for quick cable replacement, Index and Micro adjust front shifter options.