SRAM is always pushing the boundaries of what components can do. Whether it be lightweight cassettes or burly chains, SRAM makes components that are made to be dragged through the mud and come out ready to do it again the next day. Continuing this spirit of innovation is SRAM's new XX1 group. With 11-speeds, the group works flawlessly for all disciplines of mountain biking, with the most indispensable feature being the XX1 X-DOME Cassette. At first, the cassette body might have you puzzled. Where's the lockring? In order to make room for the 11th sprocket, SRAM eliminated the lockring in favor of its XD driver body. With the cassette threading at the base of the freehub body, it creates a stabler connection between the hub and the cassette. And by using the same installation tool that SRAM has relied on for years, this seemingly complicated cassette is actually easier to maintenance than any 10-speed. Though you may find yourself marveling at the XX1 design, its engagement and mud clearance outshines its looks. The single-unit X-DOME body provides the massive, 10-42t gear range an evenly spaced orientation for precise and consistent shifting efforts -- not to mention an ample range of gears to conquer any terrain. It's important to note that the XX1 cassette requires the use of a distinct freehub body. However, on a bright note, SRAM estimates that its new XD driver body is around six to eight grams lighter than a standard freehub body. For now, the XD driver body is available from three sources -- SRAM, Mavic, and DT Swiss, so you still have top-tier options for a new, XX1-compatible wheelset. The SRAM XX1 X-DOME Cassette is available in a 10-42 range and is only compatible with the SRAM XD driver body. Manufacturers currently offering freehubs compatible with the XD driver body include SRAM, DT Swiss, and Industry 9.