The 3T ARX LTD stem is a perfect match for any 3T handlebars, but they've also made a nod to the practical by making it perfectly compatible with other manufacturers' bars. This is possible because particular attention has been paid to the design of the clamp. Recognizing that modern steerer tubes and handlebars are often made from delicate composite materials, the ARX clamp interface is specifically intended to clamp the handlebar and steerer securely for even the most rugged, Roubaix-like conditions, but gently enough so to ensure that none of the clamped material is compromised. How secure-but-gentle is it? So much so that it's passed the rigorous CEN certification standards test.
3T designs their products from the inside out rather than the outside in. That means that they make use of the natural characteristics of the material in their designs. Composite materials have a 'grain, like wood, so they're stronger in one plane than another. The key to building strong, light structures using composite material is to tailor the grain of the fibers to line up along the load path. That's why the ARX LTD stem sports that impossibly sexy unidirectional carbon look rather than a more typical woven appearance.
At 118g, 3T keeps it this light by outfitting the ARX LTD with a titanium bolt package. It's available in 10mm increments from 90mm to 120mm and comes in a +/- 6 deg (84 deg). The stack at the steerer clamp is 40mm tall. It comes in a 31.8mm clamp diameter only.