There isn't much to distinguish SRAM's X5 from the more expensive rear derailleurs in the lineup, but the X5 is at a much more accessible price.  The Alloy B-Knuckle, Alloy Links, High Strength Grilon Composite P-Knuckle make up it's construction, and the result is a solid, reliable and lightweight derailleur. Direct Route cabling mean less resistance for lighter shifting and it is compatible with any of SRAM's Exact Actuation shifters to give a great performing setup. Works with up to 36T cassettes. Great for off road or town/trekking use.